The North Frontier District (NFD), or Northern Frontier Province, or simply Northern Frontier was one of the regions of British Kenya. Originally, the NFD covered the northern region of East Africa Protectorate later succeeded by British Kenya, it later included half of the Jubaland province that remained as part of Kenya when the other half was ceded to the Italian Empire.
 By the late 1920s, the Northern Frontier District covered nearly half of the colony's territory. The population of the region was estimated to be 65,136 in 1931. It was one of the most underdeveloped region of the colony and was not favoured by settlers due to its arid and semi-arid climate. In 1963, the NFD was divided into five districts across two provinces: Marsabit and Isiolo in Eastern Province; Wajir, Mandera and Garissa in North Eastern Province.
 During negotiations for Kenya's independence, Britain granted administration of the whole of the NFD to Kenyan nationalists despite an informal plebiscite showing the overwhelming desire of part of the region's population to join the newly formed Somali Republic. The North Eastern Region of the NFD is, and has historically been, mostly inhabited by Somalis.
 In present-day usage, the NFD refers to the five counties of Kenya that were established out of the five districts created by the colonial government prior to independence.
 The Northern Frontier Province existed in the East Africa Protectorate as one of nine protectorate's provinces. At the time under British colonial administration, the northern half of Jubaland was ceded to Italy as a reward for the Italians' support of the Allies during World War I. Britain retained control of the southern half of the territory, which was later merged with the Northern Frontier District.
 On 26 June 1960, four days before granting British Somaliland independence, the British government declared that all Somali-inhabited areas of East Africa, Greater Somalia should be unified in one administrative region. Which meant Kenya was to cede part of the Northern Frontier District. However, after the dissolution of the former British colonies in the region, Britain granted administration of the Northern Frontier District to Kenyan nationalists despite an informal plebiscite demonstrating the overwhelming desire of the region's population to join the newly formed Somali Republic, and the fact that the NFD was almost exclusively inhabited by ethnic Somalis.
 In December 1962, at the urging of the Somalia government, the British appointed a commission to ascertain the desires of the inhabitants of the Northern Frontier District regarding its future. The commissioners reported that the inhabitants of five of the six administrative areas of the Northern Frontier District favoured union with the Somali Republic. According to the Somali Republic, unification was favoured by 88% of the inhabitants. Early in 1963, Britain assured Somalia that no decision would be made regarding the Northern Frontier District without prior consultation with the Republic. However, Britain did not follow the wishes of the overwhelming majority of the inhabitants of the Northern Frontier District and cede the territory to the Somalia Republic. Instead, on 8 March 1963, Britain announced the creation of the North Eastern Region out of the Northern Frontier District. Unsatisfied with this solution, the Somali Republic severed diplomatic relations with the United Kingdom on 18 March 1963.
 On the eve of Kenya's independence in August 1963, British officials belatedly realized that the new Kenyan regime was not willing to give up the Somali-inhabited areas it had just been granted administration of. Led by the Northern Province People's Progressive Party (NPPPP), Somalis in the NFD vigorously sought union with their kin in the Somali Republic to the north.
 In response, the Kenyan government enacted a number of repressive measures designed to frustrate their efforts in what came to be known as the shifta period: Somali leaders were routinely placed in preventive detention, where they remained well into the late 1970s. The North Eastern Province was closed to general access (along with other parts of Kenya) as a "scheduled" area (ostensibly closed to all outsiders, including members of parliament, as a means of protecting the nomadic inhabitants), and news from it was very difficult to obtain. A number of reports, however, accused the Kenyans of mass slaughters of entire villages of Somali citizens and of setting up large "protected villages"—in effect concentration camps. The government refused to acknowledge the ethnically based irredentist motives of the Somalis, making constant reference in official statements to the shifta (bandit) problem in the area.
 Although the main conflict ended in a cease-fire in 1967, Somalis in the region still identify and maintain close ties with their brethren in Somalia. They have traditionally married within their own community and formed a cohesive ethnic network.