As recorded by Rashid-al-Din in his Jami al-Tawarikh, 4 September 1236 was the date on which the sons of Jochi - Batu, Orda, and Berke, Ugedei’s son Kadan, Chagatai’s grandson Büri, and Jenghiz Khan’s son Kulkan declared war on the Mokshas, Burtas and Erzyas.