Kairouan's lasting contribution is legal. Scholars of the city travelled to Medina to study with the students of Malik ibn Anas and brought his teaching home, and in the ninth century Sahnun compiled the Mudawwana, a vast record of questions and answers that became the basic reference of the Maliki school. A century later Ibn Abi Zayd al-Qayrawani wrote a short manual of belief and practice which has been the first book of law memorised by students from Morocco to Senegal ever since, and is still in print and in use.
Because Maliki law travelled south with the trade across the Sahara, the legal tradition of West African Islam, including the scholars of Timbuktu, descends from this city.
Kairouan's political fortunes were less steady. The Fatimids took it early in the tenth century and moved their capital to the coast, and their Ismaili doctrine sat badly with a Maliki population; when the local dynasty later returned to Sunni allegiance, the response from Egypt was to send nomadic tribes westward, and the city was sacked in the middle of the eleventh century and never regained its position.
A popular tradition ranks Kairouan among the holiest cities of Islam and holds that several visits there may substitute for the pilgrimage to Mecca. The city itself repeats the claim; many scholars reject it outright. The atlas records it as a claim rather than a status.