The earliest concrete evidence of a Muslim presence in the African Great Lakes is the foundation of a mosque in Shanga on Pate Island, where gold, silver and copper coins dated from 830 were found during an excavation in the 1980s.
Islam arrived to Tanzania with the Arab slave traders.
The route from Ujiji at the shore of Lake Tanganyika to Bagamoyo, just opposite of Zanzibar on main land Tanzania was one of the main routes of Muslim slave routes according to UNESCO data.

The history of Islam in the country can be traced to the establishment of the Kilwa Sultanate in the 10th century by Ali ibn al-Hassan Shirazi, a Persian prince of Shiraz.
The earliest concrete evidence of a Muslim presence in the African Great Lakes is the foundation of a mosque in Shanga on Pate Island, where gold, silver and copper coins dated from 830 were found during an excavation in the 1980s. Islam arrived to Tanzania with the Arab slave traders. The route from Ujiji at the shore of Lake Tanganyika to Bagamoyo, just opposite of Zanzibar on main land Tanzania was one of the main routes of Muslim slave routes according to UNESCO data.
The history of Islam in the country can be traced to the establishment of the Kilwa Sultanate in the 10th century by Ali ibn al-Hassan Shirazi, a Persian prince of Shiraz.
Islam in Tanzania