Mafia Island (“Chole Shamba”) is part of the Tanzanian Spice Islands, which consists also of Zanzibar and Pemba. Mafia is part of the Pwani Region and is governed from the mainland (not Zanzibar). Mafia has never been part of Zanzibar.
Mafia Island is also one of the 6 districts of the Pwani Region. According to the 2002 Tanzania National Census, the population of the Mafia District was 40,801. 
The people of Mafia Island are mainly fishermen; they combine their fishing activities with small scale cultivation of foods.
The island is a good retreat for adventure scuba divers, game fishermen and those seeking simple relaxation.
The Mafia island cluster consists of one large island (394km²) and many off-shore islands around it — inhabited as well as uninhabited, including Chole Island (2km²) with a population of 800. Chole Bay, Mafia’s protected deep-water anchorage and the original harbor, is studded with islands, sandbanks and beaches. The main town is Kilindoni. The stretch of water between the deltas of the Rufiji River and the island is called Mafia Channel.
Mafia Island’s history goes back to 8th century. The island once played a major role in ancient trade, between the people of Far East and mainland Tanzania. It was a regular stop for Persian boats. On the tiny island of Chole Mjini, just offshore in Chole Bay once stood a settlement, which was one of the most important towns controlling trade from the silver mines of Eastern Zimbabwe, via the old ports of Kilwa and Michangani.
In the mid 1820s, the town of Kua on Juani Island was attacked by 80 canoes filled with Sakalava cannibals from Madagascar, who ate many of the locals and took the rest into slavery.
Under a treaty of 1890 Germany took control of Mafia and constructed the buildings still evident on Chole. Germany paid Sultan Sayyid Ali bin Said al-Said of Oman DM 4 million for the island and part of the mainland coast. In January 1915 Mafia was taken by British troops as a base for the air and sea assault on the cruiser Königsberg.
Although the Cosa Nostra have, of late, been moving into the East African coast as a new avenue for money-laundering, the name Mafia probably derives from the Arabic morfiyeh, meaning “group” or “archipelago”, or from the Ki-Swahili “mahali pa afya”, meaning “a healthy dwelling-place”.