The Rangi probably formed as a distinct language group some time between 1000 and 1500 AD when Bantu language speakers from the West (more specifically, the southern shore of Lake Victoria) infiltrated the Kondoa highlands, then sparsely populated by Cushites. The Haubi valley is regarded as the cradle of the Rangi from where every Rangi's descendants originated. In reality, many who call themselves Rangi today (and are Rangi linguistically and culturally) have Cushitic ancestors.
The Kondoa highlands were a cultural backwater until ivory traders arrived between 1850 and 1880 and founded trading posts at Kondoa and Busi/Sambwa. The first mosque was built (in Kondoa) in 1885, and the first Catholic church (also in Kondoa) in 1910. Rangi were then living predominantly in the four valleys of Kondoa, Haubi, Mondo and Kolo, plus the Busi/Sambwa settlements below the escarpment. They were not centrally organized but each area had its own subchief.
After World War I, a sultan was set over all the Rangi, Sultan Salimu Kimolo, whose palace was at Kolo (his dynasty was abolished soon after Tanzanian independence in 1961).
After World War II, the bushland plains below the escarpment, up to then infested with tsetse-fly, were cleared and many Rangi moved into the Northern plains between Pahi and Kisese, the Eastern plains up to Jangalo, and the Southeastern plains from Soya to Zajilo on the border with Dodoma District. Today, there are also sizeable Rangi communities in Dar es Salaam, Dodoma, Babati and Arusha.