An Outline of the History of Restriction on Ijtihad
Among imams of the madhahib are also to be counted "the fuqaha' of the towns," mentioned by al-Maqrizi, who used either to refer to the Tabi'un or the Tab' al-Tabi'in or practised ijtihad. Among them are:
-Abu al-Harith, Layth ibn Sa'd ibn 'Abd al-Rahman al-Fahmi al-Khurasani (b. 94/712 d. 175/791 in Cairo), he was the imam of the people of Egypt both in hadith and fiqh.
-Ibn Jurayj, 'Abd at-Malik ibn 'Abd al-'Aziz (80-150/699-767), he was the imam of the people of the Hijaz during his period.
-Al-Majishun, 'Abd al-'Aziz ibn 'Abd Allah ibn Abi Salamah al-Madani al-Isfahani, faqih, hafiz and thiqah (trustworthy). Died in Baghdad in 164/780.
-'Uthman ibn `Umar ibn Musa al-Taymi  (d. circa 145/762). He was a judge during the reign of al-Mansur.
Apart from these there were other madhahib pupular in different regions whose imams, in their lifetime and later, had been authorities consulted and referred to for fatwas and ahkam, with groups of followers, big or small, among Muslims. Their fatwas were acted upon for a period of time, long or short, until they were abandoned, becoming obsolete with the passing away of their followers.
As to the madhahib which did not last for long, followed as they were by a group of Muslims only during the lifetime of their imams, there were countless. These became extinct with the death of their followers.
The aforementioned imams, apart from the differences of fatwa and opinion, also differed in respect of prestige and degrees of eminence, in their renown, and the extent of popularity or lack of it in different regions.
All this was the result of the presence of certain advantageous factors as well as those of chance in favour of some of them to the exclusion of others, or because times and circumstances were favourable to a imam and unfavourable to others.
[Factors Responsible for the Relative Influence of Some Madhahib:]