Islam in Tanzania is the second largest religion in the country after Christianity. There are no reliable statistics, figures claimed vary between 35% and "almost half" of the people of Tanzania. On the mainland, Muslim communities are concentrated in coastal areas, with some large Muslim majorities also in inland urban areas especially and along the former caravan routes. More than 99% of the population of the Zanzibar archipelago is Muslim. The overwhelming majority of Muslims in Tanzania are Sunni Muslim, with Shia and Ahmadi minorities in sub-Saharan Africa. According to the Pew Research Center research conducted in 2008 and 2009, 40% of the Muslim population of Tanzania identifies as Sunni Muslim, 20% as Shia, 20% as just a Muslim, with no further affiliation specified, and 15% as Ahm