Jagatai (jăgətī´), d. 1242, Mongol conqueror; son of Jenghiz Khan. He led large armies on his father's campaigns of conquest. When the empire was divided in 1227 among Jenghiz Khan's three living sons and a grandson, Jagatai was rewarded with vast territories that correspond to present-day Turkistan and Afghanistan. He held this domain, a key area in the Mongol empire, as a satrapy under the rule of his brother Ogadai, who, although younger than Jagatai, had become grand khan. After Ogadai's death in 1241, dissension erupted between the Ogadai and Jagatai lines, and a third branch, which had descended from Jenghiz Khan's youngest son, Tule, dominated the Mongol empire. In the early 14th cent. Jagatai's descendants, the Jagataids, divided his khanate into two sections, the western region with its capital at Samarkand, and the eastern region, centering around Kashi (Kashgar). Often at war with one another, the two domains were reunited by Timur (Tamerlane), who may have been related to the family ruling the western region. The name Jagatai is sometimes spelled Chagatai or Djagatai.