Zanzibar became the capital of the Omani empire in the 1840s and
became a British Protectorate in 1890. German East Africa was
established in 1891. The British obtained a mandate to administer
Tanganyika in 1919. In 1961 Tanganyika became independent.
Zanzibar was given independence in 1962. In 1964 an act of Union
led to the United Republic of Tanzania.
                         .
                         
Postage stamps have been issued for Zanzibar since 1895; 

for
Tanganyika since 1921; 

for 
East Africa and Uganda Protectorates, 1922, 

for 
Kenya and Uganda, 1922; 

for 
Kenya, Uganda and Tanganyika, 1935, 

for
Kenya, Uganda, Tanganyika and Zanzibar, 1964;

for
Kenya, Uganda and Tanzania, 1965, 

for 
Tanganyika and Zanzibar,1964 and 

for 
Tanzania, 1965-.