The Mahdist State, also known as Mahdist Sudan or the Sudanese Mahdiyya, was a state based on a religious and political movement launched in 1881 by Muhammad Ahmad bin Abdullah (later Muhammad al-Mahdi) against the Khedivate of Egypt, which had ruled the Sudan since 1821. After four years of struggle, the Mahdist rebels overthrew the Ottoman-Egyptian administration and established their own "Islamic and national" government with its capital in Omdurman. Thus, from 1885 the Mahdist government maintained sovereignty and control over the Sudanese territories until its existence was terminated by the Anglo-Egyptian forces in 1898.