Islam is the most prominent religion on the semi-autonomous Zanzibar archipelago and could be considered the Islamic center in the United Republic of Tanzania. Around 99% of the population in the islands are Muslim, with two-thirds being Sunni Muslim and a minority Ibadi, Ismaili and Twelver Shia. Islam has a long presence on the islands, with archeological findings dating back to the 10th century, and has been an intrinsic part in shaping mercantile and maritime Swahili culture in Zanzibar as well as along the East African coast. History of Islam in Zanzibar Origins Archeological findings suggest that Islam has been present in the Zanzibar archipelago for more than a millennium. Of the oldest archeological findings are large Friday mosque in Ras Mkumbuu, which has been dated back to the 10th Century, and Kufic inscriptions on the mosque in Kizimkazi dated at A.D. 1106. There are different historical accounts on how Islam was introduced along the East African coast, the Zanzibar archipelago included. Some suggesting that Islam was brought through Arab traders from the southern part of the Arabic peninsula, others consider the spread was initiated by groups of Zaidites from Ethiopia and Somalia, and a third group suggest that Islam came via Persia. Despite these different trajectories Islam has worked as unifying force, through which a mercantile, cosmopolitan and urban Swahili culture was formed in relation to the African hinterlands. Civilization Historically, being Swahili along the East African coast has meant having an understanding of the message of Islam and, at least nominally, some active participation. In a context of trans-cultural interactions Islam connected people via common ethics and moral conduct and placed people along the coast within a universal imaginary of the Islamic umma. Swahili townspeople were viewed to have more in common with their trade partners and fellow Muslims abroad than they had with groups in the nearby African mainland. This often meant that ancestral roots were placed outside Africa, with groups stressing shirazi origin of Persia and with Zanzibar becoming a central location for the Omani sultanate in the 1800s also of Arab descent. Over time Islam became valued as a central aspect of what it meant to be a civilized person (in Swahili muungwana, mstaarabu), that contained assigning prestige to things connected with the distant Islamic heartlands. Islam and Culture Islam after the revolution Muslim Denominations Sunni In Zanzibar today, around 90 percent of all Muslims