He was born at Sabia (now a county of Saudi Arabia). He was a grandson of Sayyid Ahmad ibn Idris al-Fasi, a native of Fez, who was head of a religious fraternity (tariqa) at Mecca and who acquired land at Sabia, settled there and died in 1837. The descendants of Sayyid Ahmed appear to have increased in wealth and influence and to have gradually supplanted the ruling sherifial family of Abu ‛Arish.
Sayyid Muhammad was educated partly at Al-Azhar University and partly by the Senussi at Kufra, and subsequently resided for a time in the Sudan, at Argo Island. On his return to Asir, his one ambition was to render that district independent of the Ottoman Empire. He gradually expanded his political power to include Mikhlaf el Yemen and a large part of the Tihamah, with control over several tribes outside these limits. He threw in his lot with the Allies in World War I, and was the inexorable foe of the Imam of Yemen.
Headley, R.L. "ʿAsīr." Encyclopaedia of Islam, Second Edition.
Anne K. Bang, The Idrisi State of Asir 1906-1934: Politics, Religion and Personal Prestige as State-building factors in early twentieth century Arabia (London: Bergen Studies on the Middle East and Africa, 1996)