Abu al-Thanaء Shihab al-Din al-Alusi (1802–54) was one of the most prominent ulama of mid-19th century Baghdad. In an era in which the Ottoman drive for modernization and centralization was changing the fabric of society and undermining the power and influence of the ulama class in large parts of the sultanate, al-Alusi was emerging as a powerful local alim, in terms of both his status as a scholar and his influence as a public figure. By the time of his death, the Alusis were becoming firmly established as a recognized ulama family, members of which would continue to play important roles in the intellectual and political life of Iraq and the Arab Mashriq. The grand Alusi, as Abu al-Thanaء al-Alusi was known, however, was, and still is, a controversial Muslim scholar whose intellectual genealogy and leanings seem to be difficult to categorize and too contradictory to pin down. Nothing illustrates the problematic of defining al-Alusi's intellectual and theological attitudes better, perhaps, than the way in which his two sons diverged. Whereas Nuעman Khayr al-Din al-Alusi (1836–99) became one of the most influential Salafi ulama in the late 19th century, his brother, Abdullah, was known as an alim with strong Sufi tendencies. Mahmud Shukri al-Alusi (1857–1924), the son of Abdullah, however, emerged as a highly regarded member of the growing Salafi circles of the major Arab urban centers in the beginning of the 20th century.