Tanganyika and Zanzibar merge to form Tanzania.

On 26 April 1964, Tanganyika and Zanzibar merged to form a new republic, the name ’Tanzania’ being adopted on 29 October 1964. Like the name of the country, the new flag adopted was a merger of that of its constituent parts. The lower green stripe of the Tanganyika flag took the blue of the Zanzibar flag, and the stripes were re-arranged diagonally to give them equal status.
Stuart Notholt, 29 Jun 1996