Tsetse fly
They were hurt by drought and disease. Thousands died in the 1880s from a cholera epidemic that was followed in 1892 by a appearance of smallpox. Rinderpest (a bovine viral disease) then wiped out their possessions.The Tanzanian government later in the 20th century re-settled the Maasai around the Ngorongoro Crater. Poaching and the absence of fires, which had been the result of human activity, set the stage for the development of dense woodlands and thickets over the next 30–50 years. Tsetse fly populations now prevented any significant human settlement in the area.