The Usambara Mountains are a mountain range of northeastern Tanzania, within the Lushoto District of the Tanga Region, in tropical eastern Africa. The range is approximately 90 kilometres (56 mi) long and about half that wide. The rock is of Precambrian metamorphic origin, and the mountains were formed nearly two million years ago by faulting and uplifting. They are split into two sub-ranges; the West Usambaras are higher and the East Usambara are closer to the coast and receive more rainfall.
The mountains are clad in virgin tropical rainforest which has been isolated for a long period and they are a centre of endemism. Historically they were inhabited by Bantu, Shambaa, and Maasai people but in the eighteenth century, a Shambaa kingdom was founded by Mbegha. The kingdom eventually fell apart after a succession struggle in 1862. German colonists settled in the area which was to become German East Africa, and after World War I it became part of the British mandated territory of Tanganyika.