Linguistic and archaeological evidence suggests that Kalenjin-speaking peoples have occupied Kenya's western highlands for the past 900 years, expanding and contracting their territories and altering their grazing and cultivation patterns in response to environmental and political pressures. Such pressures were especially pronounced during the last two decades of the nineteenth century: drought, rinderpest, and famines destroyed cattle herds and undermined human populations within and beyond the region, causing massive shifts in population. Great Britain began to establish its sphere of influence by defining and, later, enforcing political boundaries that cut through ecological zones and local and long-distance trade networks. During this period, the Pokot moved into areas that were previously occupied by the Karamojong, but they lost grazing grounds to the Turkana, who were pushing down from the north and the west. A decade after the onset of British administrative activity in 1910, the southern grazing grounds of the Pokot were alienated for European farms.
Throughout the colonial period, West Pokot was a "closed" district, a status consistent with its role as a buffer between the northernmost reaches of the "White highlands," the name given to Kenya's European-settled areas, and the shifting frontiers of Turkana. With the exception of a handful of colonial civil servants and Protestant and Catholic missionaries (the London-based Bible Churchmen's Missionary Society, which opened a station in West Pokot in 1931, and the Irish Catholic Kiltegan Fathers, who opened a school for catechumens in 1942), few Europeans ventured into the district. Government- and missionary-sponsored projects for economic and social betterment expanded after World War II, in conjunction with the rise of a grass-roots religious movement called "Dini ya Yomöt" that sought to drive Europeans out of the region. These projects focused on soil conservation, education, and health care; the latter was pioneered largely by the Catholic church, which opened the first hospital in the heart of the district in 1956 under the care of the Holy Rosary Sisters, an order of Irish nuns.
Owing to its social and political-economic isolation during the colonial period, West Pokot was the least-developed district in Rift Valley Province at the time of independence. The onset of modern infrastructure and transport, commercial townships, and land adjudication dates from the 1970s. So, too, does the expansion of primary- and secondary-school education, health-care services, religious denominations, and government involvement in the organization of women's cooperatives.