Around 56 Red seal ships to Siam are recorded between 1604 and 1635.[3] By around 1620, the trade between Siam and Japan was larger than the total trade of Siam with all other nations.[4]
A Japanese colony was established in Siam. The colony was active in trade, particularly in the export of deer-hide and sappan wood to Japan in exchange for Japanese silver and Japanese handicrafts (swords, lacquered boxes, high-quality papers). From Siam, Japan was interested in purchasing Chinese silks, as well as deerskins and ray or shark skins (used to make a sort of shagreen for Japanese sword handles and scabbards).[5]
The Japanese were noted by the Dutch for challenging the trade monopoly of the Dutch East India Company (VOC), as their strong position with the King of Siam typically allowed them to buy at least 50% of the total production, leaving small quantities of a lesser quality to other traders.
The king of Siam sent numerous embassies to Japan: in 1621, an embassy led by Khun Pichitsombat and Khun Prasert, in 1623 by Luang Thongsamut and Khun Sawat, and in 1626 by Khun Raksasittiphon.[1] Letters from king Songtham praise the relationship between the two countries:
"The existence of a sea separating Thailand and Japan has made contact between our two nations difficult. However, merchant ships of both nations now ply regularly between our two countries, causing relations to become even closer. It is now apparent that you (the Shogun) have sincere affection for us, an affection even stronger than that of our immediate kin."
—Letter by king Songtham.[1]
The Shogun responded in similar terms:
"The cordial relations between our two countries cannot be destroyed. Since we both have mutual trust, the existence of a sea between us is not of any significance."
—Letter by the Tokugawa Shogun to king Songtham.[1]