The Usambara Mountains of northeastern Tanzania in tropical East Africa, comprise the easternmost ranges of the Eastern Arc Mountains. The ranges of approximately 90 kilometres long and about half that wide, are situated in the Lushoto District of the Tanga Region. They were formed nearly two million years ago by faulting and uplifting, and are composed of Precambrian metamorphic rocks. They are split into two sub-ranges; the West Usambaras being higher than the East Usambaras, which are nearer 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.