Rashid-al-Din Hamadani
Marco Polo says Köchü had a vast number of people, but he carried on no war with anybody, and his people lived in great tranquility. Since 1280 he sent friendly letter to Kublai Khan, and the Yuan dynasty rewarded him a large amount of grains and other valuable things of China in turn for his alliance. According to Rashid-al-Din Hamadani, he also kept a very friendly relationship with his relatives, the Ilkhanate, in Persia. According to Rashid al-Din Hamadani, Köchü allied with Kaidu.