Muhammad Ali transformed Egypt from a neglected Ottoman province to being a virtually independent state. Replicating the approach of his Mamluk predecessors in the medieval Sultanate of Egypt, Muhammad Ali sought to expand Egypt's frontiers southwards into Sudan, both as a means of guaranteeing Egypt's security, and to gain access to Sudan's natural resources. Between 1820 and 1821, Egyptian forces under the command of Muhammad Ali's son conquered and unified the northern portion of the Sudan. Owing to Egypt's continuing de jure fealty to the Ottoman Sultan, the Egyptian administration was known as the Turkiyah. Historically, the pestilential swamps of the Sudd discouraged expansion into the deeper south of the country. Although Egypt claimed all of present-day Sudan during most of the 19th century, and established a province Equatoria in southern Sudan to further this aim, it was unable to establish effective control over all of the area. In the later years of the Turkiyah, British missionaries travelled from modern-day Kenya into the Sudan to convert the local tribes to Christianity. Mahdism and condominium In 1881, a religious leader named Muhammad Ahmad proclaimed himself the Mahdi ("guided one") and began a war to unify the tribes in western and central Sudan. His followers took the name "Ansars" ("followers") which they continue to use today, in association with the single largest political grouping, the Umma Party (once led by a descendant of the Mahdi, Sadiq al Mahdi). Taking advantage of conditions resulting from Ottoman-Egyptian exploitation and maladministration, the Mahdi led a nationalist revolt culminating in the fall of Khartoum on 26 January 1885. The interim governor-general of the Sudan, the British Major-General Charles George Gordon, and many of the fifty thousand inhabitants of Khartoum were massacred. The Mahdi died in June 1885. He was followed by Abdallahi ibn Muhammad, known as the Khalifa, who began an expansion of Sudan's area into Ethiopia. Following his victories in eastern Ethiopia, he sent an army to invade Egypt, where it was defeated by the British at Toshky. The British become aware of the weakness of the Sudan. An Anglo-Egyptian force under Lord Kitchener in 1898 was sent to Sudan. Sudan was proclaimed a condominium in 1899 under British-Egyptian administration. The Governor-General of the Sudan, for example, was appointed by "Khedival Decree", rather than simply by the British Crown, but while maintaining the appearance of joint administration, the British Empire formulated policies, and supplied most