West of the Nile, in Darfur, the Islamic period saw at first the rise of the Tunjur kingdom, which replaced the old Daju kingdom in the 15th century and extended as far west as Wadai. The Tunjur people were probably Arabized Berbers and, their ruling elite at least, Muslims. In the 17th century the Tunjur were driven from power by the Fur Keira sultanate. The Keira state, nominally Muslim since the reign of Sulayman Solong (r. 1660–1680), was initially a small kingdom in northern Jebel Marra, but expanded west- and northwards in the early 18th century and eastwards under the rule of Muhammad Tayrab (r. 1751–1786), peaking in the conquest of Kordofan in 1785. The apogee of this empire, now roughly the size of present-day Nigeria, would last until 1821.