In early 1964, massive riots broke out, and the Umma Party played a key role, notable for having "
prevented the revolution from taking a racial character i.e. African against Arab".
[6] Which played a political face-saving measure for the Nyerere government which was horrified with the scenes of mass killings and open-pit mass graves. The principle provocateur of the revolution; the African Nationalist John Okello had specifically demanded the killing of all Arabs between the ages of 18 and 25. The Revolution led to the
deaths of up to 20,000 mainly Arabs with widespread rape and some settlements completely wiped out. Following the state capture of Zanzibar,
racially motivated violence and persecution continued, forcing up to 75% of Arabs, Asians and Comoros Islanders to leave their centuries-old ancestral home.