In the beginning of the 20th century, all the three neighboring countries of Kenya, Uganda and Tanganyika were under British rule. In 1925 they issued their common postage stamp bearing picture of King George V. Tanganyika was then known as Tanganyika Territory. There was not sufficient space in the stamp to print its lengthy name so it was omitted. Another reason for omitting the name was that Britain was authorized to carry out administrative functions only under a mandate from the League of Nations. The printed value of stamp was 100 Pounds. Although it was valid for use as a postal stamp, the purpose behind issuing it was to raise funds for economic development of Tanganyika Territory. Some rich philatelists bought these expensive stamps. Today it is considerably more precious than its printed value.
Postage stamps and postal history of Kenya, Uganda, Tanganyika (Wikipedia)