In 1260, Marco Polo described Yarkand, part of the area under Kaidu as "five days' journey in extent"; that its inhabitants were mostly Muslim although there were also some Nestorian and Jacobite Assyrians; and that it had plenty of food and other necessities, "especially cotton." In the Toluid Civil War between 1260 and 1264, Kublai Khan was warring with his own brother Ariq Böke, who was proclaimed Great Khan at Karakorum, Kaidu began to have major conflicts with Kublai and his ally, the Ilkhanate.