Intercourse by sea between Thailand and other Asian nations had taken place since ancient times, particularly with India (Bengal and the Coromandel Coast) and Iran. During the period of European expansionism into the Far East, such intercourse was still taking place in the form of trade and exchanges of envoys. Since these ties did not have any impact on subsequent relations between Thailand and other countries, they will not be discussed here. Relations between Thailand and Japan, however, need to be mentioned.
In 1593, when King Naresuan defeated Phra Maha Uparaja, the Burmese Crown Prince, in a battle on elephant-back, his army was composed of 500 Japanese soldiers. This indicated that the Japanese had entered Thailand some time before that.
These Japanese consisted of volunteer soldiers, traders and seafarers. At the time, Japan placed restrictions on its trade with foreign countries, that is, prior permission had to be obtained for this purpose. The Japanese who left their country to become volunteer soldiers or traders were adventurers at heart, as were the Europeans who had journeyed to the Far East during the same period. Many of their actions, therefore, depicted this adventurous spirit. The Japanese volunteer corps performed well if they were kept under good supervision. However, whenever they were allowed to become involved in Thai politics, problems always arose. One case in point was Yamada Nagamasa, who was conferred the title of Okya Senabhimuk and given command over the Japanese volunteer corps during the reign of King Songtham (1610 - 1628). Yamada served King Songtham with loyalty, as evidenced by his role in supporting the King 's brother to assume the throne, as was His Majesty 's wish. Yamada also played a part in getting rid of Phya Silpa and in promoting Phra Arthityawong (August-September 1629) to the throne over King Prasattong (1629 -1656). All these actions were taken out of Yamada 's perception of what constituted loyalty. However, once he became too involved in domestic politics, which was totally unbefitting of a foreigner, disaster was to befall him and he was eventually poisoning.
The actions of Japanese citizens in Thailand during that period were entirely separate from the actions of the Japanese Government, which maintained friendly relations with Thailand. The Shokun had promoted cordial relations with the Thai Kingdom since the reign of King Ekatosarot (1605 - 1610). During King Songtham 's rule, ties between Japan and Thailand grew even closer. Thailand dispatched several envoys to Japan, namely, Khun Pichitsombat and Khun Prasert in 1621, Luang Thongsamut and Khun Sawat in 1623, and Khun Raksasittiphon in 1626. The Shogun always responded to Thai letters, such as one requesting Japan to refrain from involvement in any actions taken by Thailand to keep Cambodia in line. The Shogun replied that the Japanese in Thailand were basically traders who should not become involved in domestic affairs. Therefor, if ever they interfered in internal politics, Thai rulers were free to punish them as deemed appropriate.
The close relations between the two rulers were apparent from their correspondence. King Songtham, for example, once wrote : 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. In reply, the Shogun 's letter said : 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.
The two sides exchanged a large number of gifts. Thai fire arms and ammunition were popular among the Japanese as being of high quality. The Thais, for their part, were fond of Japanese horses. In terms of trade, Japan purchased as many as 15,000 pieces of deer skin from Thailand each year, not to mention tin, teak, sappan wood, boards, sugar, coconut oil, lead, and other commodities. The Japanese offered silver bullion and copper in exchange for the goods.
Trade between Thailand and Japan came to a halt during the reign of King Prasattong circa 1633. The main reason for this was Japan 's decision not to trade with foreign countries. The Netherlands and China, however, were allowed to carry on trade with Japan on the island of Deshima, near Nagasaki. Therefore, subsequent trade between Thailand and Japan had to pass through the Dutch and Chinese.
In sum, relations between Thailand and Japan during that period were cordial and close, although they were sometimes interrupted due to the actions of Japanese citizens in Thailand, which were unconnected to the Japanese Government. When trade relations subsequently came to a halt, this was a result of the Japanese Government 's policy of isolation caused by Japanese displeasure towards European missionaries. Thailand, however, continued to seek friendly relations with Japan, as evidence by the dispatch of envoys to that country in 1656 during the reign of King Chaiyaracha and in 1687 during the reign of King Narai (1656 - 1688).