A Title from Siam: Yamada Nagamasa and the Japanese Quarter of Ayutthaya, 1621–1630

Gunpowder for the Councillors

Yamada Nagamasa's 1621 Letter to Honda Masazumi and Doi Toshikatsu

In 1621 two of the most powerful officials in Japan received, folded in with the diplomatic business of a foreign king, a private gift of decorative sharkskin and gunpowder from a man neither of them could identify.

The sender signed himself Yamada Nizaemon Nagamasa. He was writing from Siam to ask Honda Masazumi and Doi Toshikatsu to assist an embassy from King Songtham, whose representatives were then traveling to the Tokugawa court. The request itself was unremarkable. Everything else about the letter was.

His name required investigation.

The monk and diplomatic administrator Konchi-in Sūden, who kept the shogunate’s records of foreign correspondence, went looking and came back with a connection: a former palanquin bearer in the service of Ōkubo Tadasuke, lord of Numazu. That was the man. Someone of no fixed standing in Japan was writing on behalf of a foreign crown, and the diplomatic records discussed by Yoshiteru Iwamoto show the councillors doing what officials do when a letter arrives from outside the file. They accepted the presents. They sent back cotton cloth. They addressed their reply in the form appropriate to a subordinate officer, which was the most generous reading of him the evidence permitted.

Siam had evidently found more use for him than his former countrymen had yet recognized.

What the exchange established was not a reputation for adventure but a working position. Yamada could place a letter inside an official mission, arrange the gifts that made it welcome, and ask senior Japanese officials to act. That required connections at both ends of a sea route. At Ayutthaya, the Siamese capital, he was becoming the leader of a Japanese community whose merchants and soldiers the crown found useful. In Japan, he was cultivating the men who controlled access to the shogun and the licenses under which overseas commerce operated.

Each half paid for the other. A successful trading voyage brought money and kept the contacts warm. Service to the Siamese king brought rank and authority over armed men. The arrangement worked for as long as the people issuing the appointments and the permissions remained willing to issue them.

Later biographers gave him somewhere more spectacular to end up. He became a king in Japanese memory, then a conqueror, eventually a pioneer of national expansion. In his own lifetime his advancement ran entirely through the institutions of another country: a Siamese title, troops in Siamese service, a provincial governorship under the Siamese crown. The royal authority that made the rise possible was also the thing that could take it back, and in 1630 a new holder of that authority did.

Houses Below the Capital

The Location and Population of the Japanese Quarter at Ayutthaya

The Japanese quarter stood south of Ayutthaya’s walled center, on the eastern bank of the Chao Phraya. The Portuguese settlement occupied the opposite bank. The Dutch trading establishment lay farther north. It was a working riverfront attached to a capital, where ships put merchandise and passengers ashore in a city whose rulers had dealt with foreign traders for generations and knew how to assign a newcomer a place in the commercial and political order.

The settlement was known in Japanese as a Nihonmachi, a Japanese town, and in Thai as ban yipun. The separate name did not make it a piece of Siam under Tokugawa jurisdiction. The crown permitted the community to live there and recognized a compatriot chief through whom it could be governed, which is a single arrangement rather than two: the headman who represented residents to the court was also the instrument that made them answerable to it.

Any figure for the population has to be read inside that arrangement. Counts of Japanese fighting men, of resident merchants, and of whole households are three different measurements and cannot be traded against one another. The settlement numbered several hundred, possibly rising to about 1,000 to 1,500 at its height in Yoneo Ishii’s estimate. That describes a substantial district inside an Asian capital. It does not require the thousands of armed retainers that later heroic literature supplied.

They had come for different reasons. Merchants needed a base from which to gather goods and meet ships. The political settlement in Japan had left warriors without employers, particularly after Sekigahara in 1600 and the destruction of the Toyotomi position at Osaka in 1614 and 1615, and some rōnin, masterless warriors, found work overseas. The prohibition of Christianity in 1614 pushed another movement of people toward ports where they could live and worship beyond the shogunate’s reach.

The categories overlapped. A Christian could trade. A soldier could keep a household and a commercial interest. Marriage and children tied migrants into the society around them. The quarter cannot be reconstructed by multiplying a commander’s troop strength, and the people whose work kept its houses and families running entered the record far less readily than merchants writing about cargo or officials reporting armed men.

Christianity also joined the Japanese district to the Portuguese world across the water. A Jesuit report recorded António Francisco Cardim administering the sacraments to some 400 Japanese Christians in 1627, which establishes the scale of one congregation and is not a census of the quarter. Priests and lay believers moved along a network linking Siam with Macao and Japan. For some of them Ayutthaya was a permanent refuge. For others, including missionaries looking for a way back into Japan, it was a place to wait.

So the two settlements had reasons to cooperate as well as to compete, and religious connection did not merge them into one political community. The same river carried goods between commercial rivals and priests between congregations. Its inhabitants had more relationships than the separate names on a map allow for.

A Name Under a Red Seal

Yamada Nagamasa's 1612 Red-Seal Trading License and the Shuinjō System

The early career is harder to place than the correspondence. Accounts give him different birthplaces and different occupations, running from the palanquin bearer at Numazu to an impoverished man connected with the shrines of Ise. Suruga, the province containing Sunpu, matters most to his remembered identity. Neither a precise birth date nor a continuous account of his youth is as secure as the dates conventionally printed beside his name.

One documentary foothold survives, and it is dated 1612. Birgit Tremml-Werner identifies a red-seal trading license issued to Yamada for a voyage from Nagasaki to Taiwan. That fixes a licensed maritime connection at a specific moment. It does not record his arrival at Ayutthaya. The often repeated voyage to Siam in 1612 is a reconstruction of the route by which he reached the community he later led, not a document.

The shuinjō, or red-seal permit, belonged to the Tokugawa government’s attempt to regulate overseas shipping. Its vermilion impression attached official authority to a commercial voyage, so that a ship carrying one could present itself abroad as licensed by the Japanese government and foreign authorities could tell an approved venture from an unauthorized hull. A document could not prevent every seizure or settle every quarrel at sea. It could establish whose quarrel it was.

The system also gave the shogunate an interest in people earning their living outside its territory. It could authorize their departure and correspond with the rulers who received them; those rulers could seek access to Japanese goods and ask that their own representatives be accommodated in return. Commerce supplied the vessels on which diplomacy traveled.

Siam was inside these exchanges well before Yamada was anyone in particular. Tokugawa Ieyasu corresponded with its court in 1606, and a Siamese embassy reached Japan in 1616. Earlier still, Ryūkyūan merchants had been moving Siamese products toward markets farther north. Yamada entered a relationship that already existed and made himself useful within it.

The trade gave him a great deal to be useful about. Japanese silver bought Siamese deerskins and sappanwood; the skins became leather for clothing and military equipment, and the sappanwood became dye. A shipment leaving Ayutthaya could also carry goods brought there from elsewhere in Asia, which was much of the port’s value: it gathered what no single hinterland produced.

A merchant living in the quarter could arrange purchases before a ship arrived and keep his contacts after it sailed, which is an advantage no visiting captain finishing his business in one season could match. Yamada rose among people who made their living by maintaining exactly those relationships, with suppliers as much as with officials. Military employment opened another route to influence. The letters that survive show a man who never stopped attending to ships.

The Crown’s Japanese Department

Was Yamada Nagamasa the Prime Minister of Siam? His Real Title and Command

By about 1620 or 1621 Yamada was head of the Japanese community, and his authority eventually carried the Siamese title Okya Senaphimuk. It placed him high in the kingdom’s official hierarchy. It did not make him prime minister, and it conferred no sovereignty whatever over the people he commanded.

The institution attached to him was the Krom Asa Yipun, the Department of Japanese Volunteers. The word “volunteers” misleads a modern reader into picturing an informal band of swordsmen who could be hired and dismissed. The Japanese fighting men were organized for service under the crown and could be sent on royal campaigns, and their commander’s authority ran inside that service relationship rather than alongside it. Ishii placed them under the court’s direct leadership.

Foreign soldiers offered a king one specific political advantage. Their standing depended almost entirely on royal employment, and they had few inherited connections to the established noble families, which meant they could be used against opponents whose relatives and dependents ran deep into the king’s own administration. That was a reason to recruit them. It was not a guarantee of anything. A foreign commander who stayed long enough acquired interests and allies of his own, and then he was simply another man with men.

The headman’s work was not confined to the battlefield either. He mediated between residents and the authorities, helped regulate the conduct of visiting crews, and spoke for the community’s commercial interests. A merchant dispute could become a question for the court. Trouble involving sailors could endanger a voyage. Someone able to speak for the quarter was useful to the people inside it and to everyone who had to deal with them.

That is the real shape of Yamada’s position: several kinds of usefulness held at once. Merchants needed protection and permissions. The king needed revenue and soldiers. Japanese officials needed reliable intermediaries for business in a country they did not govern. None of it required him to be the master of the trade or the indispensable servant of the kingdom, and the sources do not make him either.

The Dutch East India Company, or VOC, found the Japanese merchants of Ayutthaya serious competitors, for reasons that had nothing to do with swords: access to Japanese silver helped them secure deerskins, and long residence helped them collect supplies. Relations could still include transactions and employment across the boundary. A Dutch complaint about Japanese competition records a commercial problem, not a state of permanent hostility between everyone on both sides of it.

The same caution applies to the military reputation. Japanese troops took part in Siamese conflicts, including confrontations involving Spanish shipping, but the surviving accounts do not license the attachment of every successful action to Yamada’s personal sword. His importance does not depend on it. A foreign merchant had become a senior servant of a Southeast Asian monarchy with authority over an armed corps and a resident trading community, which is remarkable enough without the embroidery.

The Ship on the Shrine Wall

Yamada Nagamasa's 1626 Embassy to Japan and the Votive Ship Painting at Sengen Shrine

In 1626 Yamada led a Siamese delegation to Japan. Tremml-Werner’s reconstruction follows it to Sunpu and Edo, records its audience with the shogun, and identifies a permit for the return voyage from Nagasaki to Ayutthaya. He also went looking for the patronage of Sakai Tadayo, one of the senior Tokugawa councillors. The letters of 1621 had put his name into the Japanese administration. The mission of 1626 put him inside its proceedings.

He traveled as the envoy of the Siamese king, which explains his reception more accurately than any story of Japan welcoming back a conquering son. His usefulness lay in knowing how business was done at both ends. Royal letters and ceremonial gifts had to pass through officials. Requests for future voyages required approval. Personal patronage remained part of the process, exactly as it had been in the exchange with Honda and Doi five years earlier.

A painted ship belongs to the same year. An ema, a votive picture dedicated at a shrine, was offered in Yamada’s name to the Sengen Shrine at Sunpu, its inscription dated to the second month of Kan’ei three, or 1626. The dedication identified him with Suruga and with residence in Siam. A successful overseas career had been fastened to a place in Japan by way of a religious offering.

The original is gone. It burned in the great Sunpu fire of 1788, and the image survives only through copies. Iwamoto reproduces one and states the loss plainly, which is the discipline the object requires: what has come down is a representation associated with Yamada, transmitted through later hands, and it cannot be asked to carry more evidentiary weight than that.

The picture showed an armed vessel with cannon and men in Japanese armor. It belonged to a world in which a trading ship could carry substantial means of defense and a merchant could also command soldiers, which is a true thing about the 1620s and not an inventory of Yamada’s ship, still less the record of a particular victory. A votive offering communicated gratitude, hope and standing. It was not prepared for a dockyard surveyor.

The subject was nonetheless well chosen for a man whose position consisted of passage between countries. A provincial title belonged to Siamese service. A license belonged to the Tokugawa system. A ship made both authorities useful to the same person, and the dedication left a visible connection with Japan behind him when he resumed his life abroad. Centuries later, when the commercial world that produced it had faded out of popular memory, that armed ship would turn out to be an unusually convenient image on which to rebuild him.

A New King’s Letter

King Songtham's Death in 1628 and Yamada Nagamasa's Role in the Siamese Succession Crisis

Songtham died in 1628, and the succession turned into the kind of dispute in which armed support decides which member of a royal family lives long enough to reign. Yamada cooperated with the Kalahom, the senior military minister who would eventually become King Prasat Thong, in putting Songtham’s son Chetthathirat on the throne. The alliance lasted exactly as long as the minister needed it.

The broad sequence is firmer than the elaborate battle scenes often used to tell it. Chetthathirat was removed and killed. Another young prince held the throne briefly. Prasat Thong took power in 1629. The account by the Thai historian Nidhi Eoseewong, reproduced by Iwamoto, places Yamada inside the coalition that first installed Chetthathirat and then displaced him, which does not leave much room for the loyal guardian standing between Songtham’s heirs and their enemies.

Participation carried the risks of participation. A commander whose support helped settle a succession could expect influence under the winner. He could also become the obstacle an ally no longer wished to share power with. Being foreign did not hold him outside Siamese factional politics; it only meant that the men he commanded had no local loyalties, which is precisely why his intervention counted and precisely why it made him dangerous to the man he had helped.

Meanwhile the commercial and diplomatic machinery kept running. In 1629 Yamada wrote to Seki Chikara-no-suke, an intermediary connected with Sakai Tadayo, reporting Songtham’s death and announcing a mission from the new king. He had prepared a merchant ship for the envoys. A voyage intended for the previous year had been delayed. He asked for continued favor toward future trade.

It is correspondence written before its recipients could know how any of it ended. Yamada presented the new reign through the familiar apparatus of royal greetings, intermediaries and gifts, and the letter also mentions a permit received from the shogun and presents intended for both Tokugawa Iemitsu and the retired Hidetada. Diplomatic continuity had to be maintained even while the political authority behind the mission was changing hands by assassination.

The ship is what made the request practical. Without transport a royal message stayed in Siam; without recognition in Japan its carriers could accomplish nothing on arrival. Yamada stood between those two requirements, which is a large part of why his correspondence survives at all. He was doing work that officials recorded and answered.

The documents also refuse the tidy hindsight a biography wants. Letters traveled more slowly than a palace coup. An embassy could reach Japan carrying the authority of a ruler whose position had already collapsed behind it. The forms of friendship and trade went on moving along a route whose participants received the news at different times, and while Yamada’s political position grew steadily more dangerous, his written business still concerned permits, voyages, and the proper reception of a king’s representatives.

The Promotion South

Yamada Nagamasa's 1629 Governorship of Ligor and His Death by Poisoning in 1630

In 1629 Yamada received the governorship of Ligor, the southern center now called Nakhon Si Thammarat. It was a substantial appointment in a region the crown cared about, not least for its tin, and he went south with Japanese troops. In the narrative preserved by later accounts, the same appointment removed the kingdom’s most capable independent commander from the capital while the Kalahom finished taking the throne.

Promotion and removal in one document.

A distant governorship conferred rank and responsibility while separating its holder from the court where the succession was being decided, and it committed him to local conflicts that could consume the force his influence rested on. What the transfer did is considerably easier to establish than every private calculation behind it, and the distinction is worth keeping, because the private calculations are where the storytelling usually begins.

Yamada died in the south in 1630. The familiar account has him wounded on campaign and then poisoned through the dressing applied to his injury, with the new king implicated in the plot. Poisoning appears in the modern scholarly narratives, including the account reproduced by Iwamoto. The precise treatment of the wound and the identification of a particular poison are another matter, and repeated retelling should not be allowed to give them the authority of a medical record.

The fullest early narrative of the crisis came from Jeremias van Vliet, a VOC official who arrived in Siam in 1633 and wrote his historical account in 1640. He was well placed to gather information in Ayutthaya. He had not witnessed Yamada’s death. His testimony belongs to the years immediately after the events, when survivors and political interests were shaping the stories available to a foreigner asking questions, and the modern collected edition of his writings keeps that historical account distinct from his other descriptions and records of Siam, which is the right way to read a man who wrote four different kinds of document about the same kingdom.

Yamada’s son, usually rendered Oin, tried briefly to hold the family’s position at Ligor. It did not hold. The accounts describe divisions among the Japanese troops, local opposition, and the approach of forces from Ayutthaya; the survivors left, and Cambodia appears as their likely destination in the narrative quoted by Iwamoto.

The title later rendered as “King of Ligor” turned this short provincial episode into a royal achievement, which it was not. Yamada’s authority had rested on a commission from the Siamese center and on his ability to command men in the place he was sent to. His son inherited the name and discovered that the name was not the thing. The collapse of the governorship exposed the terms on which it had been granted, and they had never been generous.

The Quarter After the Fire

What Happened to Ayutthaya's Japanese Quarter After the 1630 Attack and the 1635 Travel Ban

In 1630 Prasat Thong’s forces attacked and burned the Japanese quarter at Ayutthaya. Survivors escaped downriver and fled toward Cambodia, where Japanese communities and routes of employment already existed. The violence dispersed households as well as soldiers. Yamada’s removal had left the community without the man who spoke for it; the attack then destroyed the security of the place in which its residents had built their lives.

What it did not produce was a permanent royal ban on Japanese residence. Groups returned in the early 1630s and the settlement began to recover. Japanese soldiers again entered royal service, which is evidence that the new regime went on finding uses for people from the community it had just burned, and evidence of nothing else. It does not show that every survivor returned, or that rebuilding restored what had been lost.

The destruction changed the circumstances of the trade without touching the demand underneath it. Deerskins still had buyers in Japan. Siamese suppliers still wanted silver and other imports. The Dutch had commercial reasons to welcome the weakening of a competitor, and commercial advantage is not evidence of Dutch responsibility for the attack; the royal struggle and the contest over supplies intersected without becoming a single conspiracy.

The change that finally mattered came from Japan. In 1635 the Tokugawa government prohibited Japanese overseas travel and return, ending the licensed voyages that had sustained the movement of people between Japan and Southeast Asia. The exclusion of Portuguese ships in 1639 was a separate measure in the same tightening of foreign relations. Between them they remade the world in which the overseas Japanese settlements had grown.

For the residents of Ayutthaya the effect was specific. The interruption of migration removed the means of renewing the community: no new merchants, no relatives, no prospective employees arriving through the Japanese shipping system, and no way home for those already abroad. Local marriage and the passage of generations went on changing the settlement’s identity from the inside. Neither the fire nor the travel ban accounts for that longer process on its own.

The goods kept crossing. Chinese-operated junks and Dutch ships supplied Japanese markets, and vessels from Siam still reached Nagasaki; Ishii’s study of the Japanese documents records no fewer than 130 such arrivals between 1647 and 1700. Classified within the permitted junk trade, the commercial connection survived the collapse of the diplomatic one.

That later commerce had no particular need of a man in Yamada’s position. Ships could carry Siamese goods under arrangements that no longer sent Japanese emigrants south or Japanese envoys north. The route outlasted the institutions and the people who had maintained it. Merchants of Japanese descent remained part of Ayutthaya’s history for a long time afterward; what had ended was the brief concentration of commercial and military weight in a single court officer.

An Overseas Career Reissued

How the 1942 Japanese Textbook Turned Yamada Nagamasa Into a National Hero

Yamada’s modern fame began with a revival of Japanese interest in expansion toward the south. From the late nineteenth century, newspapers and historians went back to the overseas communities of the red-seal period, and a man who had become powerful in Siam made an exceptionally usable predecessor. His trade and his military service could be presented as proof that Japanese enterprise had reached beyond the home islands centuries before anyone thought to plan it.

The reinterpretation reversed the direction of his allegiance. In the documented career, Yamada advanced by serving a Siamese king. In the expansionist account, his achievements abroad demonstrated the power and promise of Japan. The Japanese quarter became a national outpost. Armed men attached to a foreign crown became precursors of a later southern advance. The incidents stayed the same and acquired an entirely different purpose.

Scholarship made the earlier world available in the first place. Murakami Naojirō worked through European archives and Japanese documentary compilations and brought the material on overseas trade to a wide readership. When the history of the Southern Seas was institutionalized at Taipei Imperial University in 1928, with Murakami as its first chair, that work was placed inside an institution of Japan’s colonial empire, as Tremml-Werner’s study of his career sets out. His biography of Yamada appeared in 1942. Source criticism and imperial interest were housed in the same building, on the same shelves, sometimes in the same book.

A Japanese moral-education textbook of 1942 made the appropriation explicit. It praised Yamada’s achievements as a contribution to Japanese national glory, and Iwamoto reproduces the passage, with its inflated community and its heroic account of military service. Siam supplied the setting in which Japanese qualities were demonstrated. The people whose king employed him receded behind the exemplary foreigner, which is what happens to the setting in that kind of story.

That history has complicated every later attempt to celebrate Yamada as a figure of international friendship. His correspondence did connect two courts. His political activity also involved armed intervention in a royal succession. And the merchants, soldiers and Christian refugees around him cannot be made to express one national purpose between them, because their reasons for leaving Japan were not the same and neither were the lives they built in Siam.

The painted ship went through its own changes of meaning. Its dedication belongs to 1626, when the career it commemorated was still in progress. The shrine fire of 1788 destroyed the object. Copies carried the image forward, and one of them was reproduced in the Siam Society’s journal in 2007, still showing the vessel with its cannon and its armored men. Underneath it the caption gives the date of the dedication and then, in a single parenthesis, the status of the picture: a copy.

Sources & Further Reading

Ishii, Yoneo. “Seventeenth Century Japanese Documents about Siam.” Journal of the Siam Society 59, part 2, 1971, pp. 161–175. Consulted for the early diplomatic correspondence, the population of the ban yipun, and the count of Siamese arrivals at Nagasaki after Japanese travel was prohibited.

Ishii, Yoneo. “Siam and Japan in Pre-Modern Times: A Note on Mutual Images.” In Multicultural Japan: Palaeolithic to Postmodern, edited by Donald Denoon, Mark Hudson, Gavan McCormack, and Tessa Morris-Suzuki. Cambridge University Press, 1996, pp. 153–159. The source for the earlier Ryūkyūan link between Siamese products and markets to the north.

Ishii, Yoneo. “Material Exchange without Human Contact: Pre-modern Japan–Southeast Asian Relations.” Lecture to the Asiatic Society of Japan, 15 April 2002; summary compiled by Hugh E. Wilkinson and Doreen Simmons. Used for trade goods, migration and the Japanese community, with the caution that a published summary is a report of a lecture and not a transcript of one.

Iwamoto, Yoshiteru. “Yamada Nagamasa and His Relations with Siam.” Translated by Simon James Bytheway. Journal of the Siam Society 95, 2007, pp. 73–84. The indispensable article: translated letters, the votive picture and its destruction, Nidhi Eoseewong’s reading of the succession, and the 1942 textbook, though its unusually precise account of Yamada’s origins is not adopted here as settled fact.

Polenghi, Cesare. Samurai of Ayutthaya: Yamada Nagamasa, Japanese Warrior and Merchant in Early Seventeenth-Century Siam. White Lotus Press, 2009. A focused study of Yamada, the Japanese community, and the later representations of both.

Tremml-Werner, Birgit. “Narrating Japan’s Early Modern Southern Expansion.” The Historical Journal 64, no. 1, 2021, pp. 139–161. The source for the 1612 license, the 1626 embassy, and the relationship between Murakami’s archival scholarship and the southern-expansion narrative it was made to serve.

Tremml-Werner, Birgit. “Samurai in Southeast Asia: The Lives and Afterlives of Takayama Ukon and Yamada Nagamasa.” Japan Review 41, 2026, pp. 83–105. A recent comparison of two overseas careers and of the commemoration that followed them.

Van Vliet, Jeremias. Van Vliet’s Siam. Edited by Chris Baker, Dhiravat na Pombejra, Alfons van der Kraan, and David K. Wyatt. Silkworm Books, 2005. The collected English translations of Van Vliet’s four accounts, including a new translation of his narrative of the succession, which is the fullest near-contemporary source for the crisis that killed Yamada.