Although there are no written records, it seems likely that Chiang Saen flourished as the centre of a small kingdom called Yonok between the 6th and 10th centuries CE. According to legend, the city was founded in 545. By the 12th century Yonok had emerged as a centre of power for the Tai peoples gradually migrating southward from Yunnan to the Maenam Chaophraya Valley. In 1261 King Mangrai succeeded his father as ruler of Chiang Saen and soon began a series of conquests to the south, ultimately capturing Chiang Mai in 1296. Yet these very successes spelled the end of Chiang Saenˇs importance, and the city gradually fell into decline, cast into shadow by the emerging glory of Chiang Mai. At the beginning of the 19th century, Chao Kawila captured Chiang Saen and transported its people back to Chiang Mai where they were forcibly resettled. Chiang Saen was left depopulated and in ruins until the 20th century, when it gradually recovered.