Chaghatāy’s descendants sought to expand the area under their control, originally conquered by Chingīz Khān, and according to Rashīd al-Dīn Faḍl Allāh ‘in the time of Ögedey in the year 634/1237 Chaghatāy’s sons and grandson Būrī . . . waged war on Boqshi and Burṭās and Burjān which they soon captured’ (1/668).

According to the mediaeval Persian sources, when dividing the vast territories under his control among his sons, Chingīz Khān specified the regions stretching from Uyghūr to Samarqand and Bukhārā, with Almālīq (650 km northeast of Lake Iss…