Wei Yuan
Thailand was always subordinate to China as a vassal or a tributary state from the Sui dynasty until the Taiping Rebellion of the late Qing dynasty in the mid-19th century. The Sukhothai Kingdom established official relations with the Yuan dynasty during the reign of King Ram Khamhaeng. Wei Yuan, the 19th century Chinese scholar, considered Thailand to be the strongest and most loyal of China's Southeast Asian tributaries, citing the time when Thailand offered to directly attack Japan to divert the Japanese in their planned invasions of Korea and the Asian mainland, as well as other acts of loyalty to the Ming dynasty. Thailand was welcoming and open to Chinese immigrants, who dominated commerce and trade, and achieved high positions in the government.