On 12 January 1964, a month after independence, an armed uprising overthrew Sultan Jamshid bin Abdullah and the Arab-led government of Zanzibar. Britannica records that the revolt was carried out by only about 600 armed men under John Okello but drew wide support from the African population, and that thousands of Arabs were massacred in the ensuing violence while thousands more fled. Estimates of the dead vary enormously and none rests on a body count: academic estimates cited in the press range from 5,000 to 15,000 Arabs killed, the BBC has cited up to 17,000 including South Asians, and other historians consider figures in the low thousands more plausible. Thousands were also imprisoned. The revolution installed Abeid Amani Karume as president; Zanzibar united with Tanganyika in April 1964 to form Tanzania. Property confiscations and discriminatory decrees under Karume drove continued emigration of Arabs and South Asians through the 1960s and 1970s, chiefly to Oman. No inquiry into the killings was ever conducted.
Insurgents of the Afro-Shirazi movement overthrew the Sultanate of Zanzibar and killed and expelled members of the island's Arab and South Asian minorities
The 1958 census of the protectorate counted about 299,000 people in all, of whom roughly 50,000 were classified as Arab and 20,000 as Asian, in a population overwhelmingly of African and Shirazi origin. Killings in January 1964 are estimated at anywhere from several hundred to 20,000, and most of the surviving Arab and South Asian population left within a few years.
The range spans academic estimates of 5,000–15,000 Arabs killed and a BBC figure of as many as 17,000 including South Asians, as reported by Middle East Eye. Lower estimates in the low thousands also circulate. The disagreement is driven by the absence of any official inquiry, the burial or disposal of bodies without record, and the political sensitivity of the episode in Tanzania.
Massacres are described by Britannica and the imprisonment of thousands is reported by Middle East Eye; no formal investigation has ever documented the events in detail.
Tanzania, Oman