The Maasai migrated south from Northern Africa, probably in the region of the Nile Valley in Sudan, northwest of Lake Turkana, sometime between the 14th and 16th centuries, before establishing themselves in the Eastern region of Africa in the mid 17th century. They quickly spread south through the Rift Valley, whose fertile grasslands were ideal for their cattle, and around the 17th or 18th centuries reached their present-day territories in Kenya and Tanzania, where they were feared and renowned as warriors.
From 1830 onward, Maasai unity disintegrated into a succession of wars between the various clans, largely over cattle and grazing grounds, which led to territorial losses and gains by their neighbours. By the end of the 19th century, their neighbours and British colonists had displaced the Maasai from the rich lands of the central Rift Valley - the area between Lake Victoria and Mount Kenya. The infamous 1904 Maasai Agreement drawn up by the colonial power had effectively reduced their territory by two thirds. A further wave of forcible 'relocation' took place in 1911-13, confining the Maasai to distant reserves in southern Kenya and Tanzania.
The Ngorongoro Conservation Area was created in 1959 as a separate part of the Serengeti National Park. The Maasai were allowed to live in the Ngorongoro Conservation Area but were excluded from the National Park. The Maasai elders who agreed to this deal subsequently said they did not know what they were signing. Previously a combination of wildlife experts and palaeontologists, including Louis Leakey and Bernard Grzimek (author of Serengeti Shall Not Die), had campaigned to remove the Maasai from the whole of the Serengeti/Ngorongoro area and make the whole area a national wildlife park.
Post independence, tourism was developed around big game watching from game lodges in the Serengeti and Ngorongoro. In the 1990s, when such tourism begun to yield high revenues, there was pressure to increase the game reserves and Ikorongo and Grameti Games Reserves were added to Serengeti's western border and the local people once again removed. Since then there have been moves to create Wildlife Conservation Areas to the north of the Serengeti: the Maasai complained in a case that went to the Tanzanian Human Rights commission.
Within the Ngorongoro Conservation Area, the Maasai have increased in numbers from around 10,000 in 1960s to just over 60,000 today. There were moves from 1975 to ban agriculture in the area and in 1992 the Government indicated that Ngorongoro should be for wildlife and the Maasai be encouraged to move. In 2003, 200 families were evicted as illegal immigrants. The Maasai are currently only in part of the nominated area (in spite of the fact that the 1959 agreement allowed them to live in the whole).