Kublai Khan the role of Emperor of China. By 1279, the Mongol conquest of the Song dynasty was completed and Kublai became the first non-Han emperor to conquer all of China. The imperial portrait of Kublai was part of an album of the portraits of Yuan emperors and empresses, now in the collection of the National Palace Museum in Taipei. White, the color of the royal costume of Kublai, was the imperial color of the Yuan Dynasty. Kublai Khan was the fourth son of Tolui, and his second son with Sorghaghtani Beki. As his grandfather Genghis Khan advised, Sorghaghtani chose a Buddhist
Mongol invasions of Vietnam repeatedly ignored demands to attend the Yuan court and offer his personal submission to the Great Khan. By 1266, a standoff developed, as the Emperor Thánh Tông sought a loose tributary relationship, while Kublai demanded full submission. Trần Thánh Tông sent an official letter requiring Kublai to take his darughachi back. Because of civil war in the Mongol Empire, and the Yuan conquest of Song China, armed conflict was delayed. Instead, Kublai reminded him of the peace treaty signed by the Mongols and Đại Việt. As a result of the Mongol conquest of the Song Empire, by 1278–79, Mongol troops