In 1856 the islands of Zanzibar and Pemba became an independent state under the name of "Sultanate of Zanzibar and Pemba." The sultans issued their own coins; the currency unit was the pysa. 4 pysa equaled 1 anna, 64 pysa equaled 1 rupee and 136 pysa equaled 1 riyal. The name pysa derived from paisa, an old Indian copper coin that had been issued since the 16th century in diverse weights. The Sultanate of Zanzibar and Pemba came under British control in 1890 and was integrated into the British colonial empire in 1897. Today the islands are part of Tanzania.