Terrorist attacks on the United States on 11 September 2001 overlapped with ongoing movements of Islamic fundamentalism in sub-Saharan Africa; however, these movements have not been identical, nor have they encountered uniform responses from the governments overseeing them. This is evident in the Hausa borderlands of Niger and Nigeria, where I conducted fieldwork (first begun in the early 1980s) two months after the attacks. Differences in the application of shari'a (Islamic law) on both sides of the border accentuate differences in Hausa culture and society along national (i.e., Nigérien vs. Nigerian) lines. Traditional Hausa customs that have flourished for centuries (praise-singing, drumming, group dancing, and singing) are now proscribed in the northern Nigerian state of Katsina, where shari'a is tantamount to de-Africanization. In contrast, Zinder, a neighboring state in the Republic of Niger, has so far resisted a comparable Islamization of its legal code. Cultural differentiation across the Niger-Nigeria boundary persists along religious lines, despite the status of Islam as the common faith. This inflected globalization of Islam highlights the significance of national boundaries in delimiting the influence of religious revivalism. Other differences relating to Islamization are inferred from comparing the extent of pilgrimage to Mecca and the incidence of wife seclusion in neighboring Hausa villages on each side of the Niger-Nigeria boundary.