Both [cities] had long been sites of religious thinking, but it was only in the seventeenth century that their efforts to reconsider the Hadith Reports made them intellectually prominent. The scholars reviewed basic Shari'a documents with an eye to purifying society of non-Islamic practices. As in the Protestant Reformation, the assertion of the right to reconsider old decisions was in ways even more important than the specific content of that review. Even though these scholars (like Martin Luther) had a profoundly conservative intent, their activities had a radical effect, clearing the way for others too to re-examine the Islamic record and draw new conclusions. The efforts of scholars in Mecca and Medina became known throughout Islamdom via the hajj, as pilgrims each year returned from the Hijaz bearing new ideas.
Some of the more prominent disciples of the scholars included: (1) Jabril ibn Umar, who studied in Cairo and taught the new ideas to Uthman dan Fodio; in 1804, the latter launched the Fulani jihads in the northern Nigeria area which convulsed the region for decades. (2) Muhammad ibn 'Abd al-Wahhab studied for many years in Mecca and founded a movement that came to be named after him, the Wahhabiya, probably the most extreme fundamentalist movement ever to succeed politically. In 1744, he formed an alliance with a tribal leader, Muhammad ibn Sa'ud which assured the Wahhabis a lasting voice in Arabian politics. In turn, the Wahhabis influenced other fundamentalists; for instance, a Moroccan sultan sent a delegation to Mecca in 1812 to learn about Wahhabi practices. (3) A Moroccan scholar, Ahmad ibn Idris, studied in Mecca and later established an independent state, run by religious leaders, in Asir province, to the south of Mecca. (4) Shah Wali Ullah, the outstanding Islamic thinker of India, studied in the Hijaz in the early eighteenth century. (5) Shariat Allah, the founder of the Fara'idiya, a fundamentalist movement in Bengal, studied in Mecca for twenty years before returning home and agitating for fundamentalist goals. (6) Abd ar-Ra'uf as-Sinkili studied for nineteen years in Arabia before going back to Indonesia and spreading a Neo-Sufi order. (7) Abd as-Samad al-Palimbani studied and taught in Mecca before he too returned to Indonesia to propagate a brotherhood. (8) Three scholars returning from Mecca called for stricter legalism and founded the Padri movement of Sumatra. (9) Ma Ming-hsin of Kansu province in China studied on the Arabian peninsula before establishing the New Teaching which later fomented a revolt against the Chinese authorities.