Turkistan, Transoxiana, and the adjacent regions were controlled directly by his descendants but not Kashghar, Yarkand, Khotan, Aksu, and the southern slopes of the Tian Shan mountains—or, in other words, to the province south of the line of the Tian Shan. As regards this province, Mirza Muhammad Haidar Dughlat says that it was given by Chagatai, presumably at his death, to the clan or house of Dughlat, whose members were reckoned to be of the purest Mongol descent, and one of the noblest divisions of that people. The Dughlats were thus made hereditary chiefs, or Amirs, of the various districts of Eastern Turkestan, as far back as the time of Chagatai, for it is chiefly on this incident that hinges the permanent division of the Chagatai realm into two branches, at a later date.