By Kublai Khan’s death in 1294, the Mongolians ruled four ulus, or domains, each of which ultimately crumbled: Kublai Khan’s homeland region, including Tibet and China; the central steppes of the Chagatai; the Ilkhans’ Persia and Transoxiana; and the western forest zones of the Golden Horde. Understand how each fell away from the Mongol imperial legacy.