The history of Anglican Diocese of Zanzibar is well inter-related with the history of University Mission of Central Africa and the abolition of Slave Trade in Zanzibar.

Slave trade in Zanzibar was initiated by Portuguese who traded slaves in the 15 century. Portuguese were conquered in the war by the Oman in 1549. Zanzibar gradually built her transit trade from economic foundations achieved in the later part of the 18th century.

From the early decades of the 19th century, Said bin Sultan (ruler of Zanzibar 1804 – 1856) moved his Capital from Muscat Oman to Zanzibar and encouraged among other things a broad range of commerce in the region. Slave trade was part of the Zanzibar commerce.

Slave trade was promoted Under the Oman Arab rule and resulted in the opening of the new slave market at Mkunazini. The Arabs continued with the slave trade until it was abolished by a treaty of June 6, 1873. Slaves were obtained from the open market and about half of them were formerly captured from the mainland.

They were transited at coastal ports such as Kilwa, Kaole, Bagamoyo and Pangani (on the mainland coastline) before packed on board the dhows to Zanzibar.