Nguyen Hoang

• Died: 1613
• Vietnamese: 阮潢 (Nguyễn Hoàng)

Nguyễn Hoàng was Chúa (Lord) of central-southern Vietnam (a territory known as Quang Nam) from 1600 until his death in 1613. He played a significant role in the development of the region, and especially of its chief port, Hoi An, as well as being the Lord of Quang Nam who established formal relations with Toyotomi Hideyoshi and Tokugawa Ieyasu.

The earliest extant document reflecting communications between Nguyễn and Japan is a letter from Nguyễn Hoang dated 1591. Addressed to the "King of Japan" and likely carried to Japan by a Japanese merchant active in regional maritime trade, the letter essentially offers gifts and asks for the establishment of formal relations. The outcome of this communication is unclear. However, Nguyễn is known to have contacted Japan again c. 1599-1601, after having captured the pirate Shirahama Kenki, and requesting instructions as to what to do with him. Tokugawa Ieyasu's response, dated 1601, was long considered the earliest extant evidence of formal Vietnamese-Japanese relations, prior to the 2013 discovery of the 1591 document. In this 1601 letter, Ieyasu explained the red seal ship system - essentially, that authorized Japanese merchants possessed a license with an official red seal, and that others, who did not possess such a license, such as Shirahama, were under no protection of the Japanese authorities and could be dealt with as Nguyễn chose. Some fifteen letters exchanged between Nguyễn and Tokugawa, dated between 1601 and 1613, are known to be extant.

In 1604, Nguyễn formally adopted the Japanese merchant Funamoto Yaheiji. From then on, he had Yaheiji serve as his official representative in communications and relations with Japan.