Maa-speaking Plains Nilotic pastoralists whose sections (Purko, Kisongo, Loita, Laikipiak, Uasin Gishu, Kaputiei) held a near-monopoly of the Rift Valley grasslands from the Uasin Gishu plateau to the Maasai Steppe. Internal Iloikop wars of c. 1830–1870s destroyed the Laikipiak and Uasin Gishu sections, and rinderpest and smallpox in the 1890s preceded British and German protectorate rule.
Not an ending: the Maasai remain one of the best-known nations of Kenya and Tanzania, holding Kajiado, Narok, Ngorongoro and the Maasai Steppe. The map hands off to the East Africa Protectorate (1895) and German East Africa, which cover the same ground continuously thereafter.
The standard scholarly collection on Maasai history, sections and identity; verified via Open Library (OL25786732W, ISBN 9781782047803).
Contemporary Oxford ethnography whose introduction records the Maasai range, section districts and the Iloikop wars; full text open on the Internet Archive.