Mafia Island, Tanzania, lies off the mouth of the Rufiji River in Southern Tanzania. It is one of the least developed parts of an undeveloped country, yet it has been, and continues to be, part of important historical processes. Although its spectacular marine life is becoming increasingly well known, especially since the setting up of the Mafia Island Marine Park.
 

Mafia, along with the other islands lying off the east coast of Africa, has shared in the long and interesting history of the area. The East Coast forms a part of the Indian Ocean littoral, and the peoples of this region have been traders and sea-farers for centuries. It is an area exceptional in Africa because it is mentioned in written accounts which go back as far as two thousand years. The earliest is a Greek text, the Periplus of the Erythraen Sea, which is dated around A.D. 110. Most subsequent accounts, up to the arrival of the Portguese on the coast in the fifteenth century, were written by Arab geographers.

By the end of the first millenium A.D. there had been established a number of Islamic city-states based on trade the most important of which were initially on Zanzibar and Pemba Islands. By the thirteenth century, however, the chief settlement on the coast was Kilwa Kisiwani, a small island lying about 80 miles to the south of Mafia. Kilwa owed its prosperity mainly to the fact that it controlled the gold-trade from Sofala (now in Mozambique).

One of the earliest documents relating to the coast is the Kilwa Chronicle, of which two versions survive, one in Arabic and the other in Portguese. In this book, Kilwa is said to have been founded by the sons of a sultan from Shiraz in the Persian Gulf, who migrated in the tenth century A.D. The Kilwa Chronicle goes on to record that some of the sons of the first Kilwa sultan settled on the southwestern tip of Mafia Island, which is today called Kisimani Mafia.