MAHDI, mä'dḗ (Ar. al-Mahdī, the Guided One) . The name given to the messenger of Allah, who is expected by certain sections of the Mohammedan world to complete the Prophet's work by converting or exterminating the infidels and by equitably dividing the world's goods. It is supposed that he will be a second Mohammed in name and in appearance; and, since the time of the Abbassides, that he will carry the black flag of the Prophet. He is to meet Jesus in Damascus and Jerusalem, and to reign seven, eight, or nine years, filling the earth with justice. The idea is not contained in the Koran; but later tradition puts the following words into Mohammed's mouth: “Even though time shall have but one more day to last, God will call up a man of my family who will fill the earth with justice, as it is now filled with iniquity.” The Mahdi idea arose in the eastern part of the new Arab empire, nourished by Jewish ideas of the coming of the Messiah, and Christian ideas of the second coming of Jesus; more especially in Persia, where the idea of a Saoshyant (q.v.) or Redeemer was part of the popular tradition and the trend to mysticism and deification part of the national character. Its first manifestation was due to the anti-Arab feeling of the Persian Mohammedans who, as legitimists, gathered around Ali, the son-in-law of the Prophet, and resented his neglect in favor of the Ommiads, the bitterest opponents of the Prophet, Even during his lifetime Ali was deified, though against his will, by the Jew Abd Allah ibn Saba; and his violent death strengthened the belief that he would be awakened at the end of time and would conquer the world. By others Ali was considered simply to be the wāṣi or vicar of the Prophet; and in the circles which regarded him as the legitimate Imam (leader) he was confounded sometimes with the Messiah, sometimes with Elijah. The subject became one of fierce dispute between the Shiites and the Sunnites. In the course of time the idea was used as a political weapon by numerous pretenders, and the Mahdi led the Holy War (jihad) against Moslems as well as against unbelievers. The first Mahdi was Mohammed ibn al-Hanafiyyah, son of Ali, though not of Fatima, who was proclaimed by one Mukhtar in the reign of Abd al-Malik (684-687) after the murder of Ali's son Hosein. When Mohammed died the Persians refused to believe him dead, but asserted that he would return after seventy years. The idea spread, and since then Mahdis have arisen very often among Persians, Egyptians, and the Arabs of the Sudan. One of the most famous of these was the veiled prophet Al-Mokanna (see Hakim ibn Allah), the subject of Moore's poem, who came to be regarded as divine and was worshiped for centuries. A large number of Shiites believe that there have existed only twelve Imams. When the twelfth died at Samarra (941), a child of twelve years, it was held that from that time on the Imam would remain concealed, though he may arise as Mahdi at any moment. Of the Egyptian Mahdis, the mad Hakim (996) is most notorious. He also disappeared, but that he will appear again is the firm conviction of the Druses (q.v.) in the Lebanon Mountains and the Hauran. Of the sects that have sprung from this idea, the Ismailis may be mentioned, who expect the return of a Mahdi, Mohammed ibn Ismail of the family of Ali. The Karmathians also took their origin from this idea. (See Mohammedan Sects.) Even orthodox Islam has been affected, and had its Mahdi in the person of Ibn Tumart (1121), the founder of the Almohade Berber power.
The modern Mahdi is a product of one of the many religious orders (the Sammaniyyah) which, as a protest against the encroachment of the Christian civilization, honeycomb the Moslem world, and are especially numerous in Northern Africa. Born in 1844 or 1848 in the Province of Dongola, he took the name Mohammed Ahmed, asserting that his father was descended from Hosein and his mother from Abbas. He studied at Kereri, four miles north of Omdurman, at Khartum and in Berber. In 1870 he allied himself with the Sammani order, passing part of his time with his uncle, a shipbuilder on the island of Aba in the White Nile, where he lived an ascetic life. He then entered a minor order at Musallemia on the Blue Nile. In these circles the year 1882 (A.H. 1300) was supposed to be the Mahdi year, Mohammed soon became famous in the country between the White and the Blue Niles. He was joined in Kordofan by a Bakkara Bedouin named Abd Allah, who afterwards became his Caliph. He was proclaimed Mahdi in El-Obeid in 1880, but returned to Aba to continue his ascetic life. In May, 1881, he came forward openly and sent circulars to the chiefs of Islam preaching the Jihad, or Holy War, the conversion of all unbelievers, a return to the simple faith of the Prophet, simplicity in dress and manners, and a sort of social communism and asceticism. Afraid of the Egyptian Government, he collected a band of Dijera and Kinaru Bedouins and proclaimed the Jihad. In July, 1881, a small expedition sent against him was destroyed on the island. Imitating the Prophet, he left Aba, his Mecca, and came to Masa in Southern Kordofan, which he proclaimed his Medina. For his subsequent movements, see Sudan. He died of smallpox. Consult: Darmesteter, The Mahdi (New York, 1885); G. Hoffmann, Mahdithum (Kiel, 1899); Snouck Hurgronje, in Revue Coloniale Internationale (1886); Ernst Müller, Beiträge zur Mahdilehre des Islams (Heidelberg, 1901).