Khan in 1227, his empire was divided among his four sons and his family members. Despite the potential for serious fragmentation, Mongol law of the Mongol Empire maintained orderly succession for several more generations, and control of most of Mawarannahr stayed in the hands of direct descendants of Chaghatai, the second son of Genghis. Orderly succession, prosperity, and internal peace prevailed in the Chaghatai lands, and the Mongol Empire as a whole remained strong and united. Rule of Timur and Timurids In the early 14th century, however, as the empire began to break up into its constituent parts, the Chaghatai territory also was disrupted as the princes of various tribal groups competed for influence. One tribal chieftain, Timur (Tamerlane), emerged from these struggles in the 1380s as the dominant force in Mawarannahr. Although he was not a descendant of Genghis, Timur became the de facto ruler of Mawarannahr and proceeded to conquer all of western Central Asia, Iran, the Caucasus, Asia Minor, and the southern steppe region north of the Aral Sea. He also invaded Russia before dying during an invasion of China in 1405. Timur initiated the last flowering of Mawarannahr by gathering in his capital, Samarkand, numerous artisans and scholars from the lands he had conquered. By supporting such people, Timur imbued his empire with a very rich Perso-Islamic culture. During Timur's reign and the reigns of his immediate descendants, a wide range of religious and palatial construction projects were undertaken in Samarkand and other population centers. Timur also patronized scientists and artists; his grandson Ulugh Beg was one of the world's first great astronomers. It was during the Timurid dynasty that Turkic, in the form of the Chaghatai dialect, became a literary language in its own right in Mawarannahr, although the Timurids were Persianate in nature. The greatest Chaghataid writer, Ali Shir Nava'i, was active in the city of Herat, now in northwestern Afghanistan, in the second half of the 15th century. The Timurids supported the development of literature in the Turkic language. In 1398, Timur's son Miranshah ordered to draw up an official document in the Turkic language in the Uyghur script. Timur's grandson Iskandar Sultan had a court that included a group of poets, for example, Mir Khaidar, whom Iskandar encouraged to write poetry in the Turkic language. Thanks to the patronage of Iskandar Sultan, the Turkic poem "Gul and Navruz" was written The Timurid