Kenya–Tanzania border

A line between two spheres of influence

In 1886 Britain and Germany agreed to split East Africa into two “spheres of influence”: Britain's to the north of a line, Germany's to the south.^[1] The line started on the Indian Ocean near Vanga and ran inland to the eastern shore of Lake Victoria, where the 1st parallel south meets the shore, just north of today's port of Shirati.^[1]

Between those two ends the agreement named only a few landmarks. It ran straight to Lake Jipe, went round its eastern and northern sides, passed between the lands of Taveta and Chagga, skirted the northern base of Kilimanjaro, and then ran straight to Lake Victoria.^[1] Because the line passes north of the mountain, Kilimanjaro fell on the German side, and it is in Tanzania today.^[1]

In 1890 a second Anglo-German agreement repeated almost exactly the same line and carried it west across Lake Victoria along the 1st parallel south.^[1]

“…skirts the northern base of the Kilimanjaro range, and thence is drawn direct to the point on the eastern side of Lake Victoria Nyaza (Lake Victoria) which is intersected by the 1st degree of south latitude.”^[1]

Fixing the details on the coast and the mountain

A treaty of 25 July 1893 moved the starting point on the coast to the high-water mark on Ras Jimbo, a small headland. From there a straight line runs to the point where latitude 3°40′40.3″S meets the eastern bank of Lake Jipe.^[1] Near the sea the line takes a short detour along creeks, and an Anglo-German protocol of 1900 set out that detour in detail, using mangrove posts, cement blocks and marks cut into baobab trees.^[1]

Inland, a joint British and German commission surveyed the line from Lake Jipe to Lake Victoria in 1902–06 and marked it with pillars of stone and earth. Demarcation means marking a line on the ground, as opposed to delimitation, which means agreeing it on paper.^[1] The two governments signed an agreement based on this work in Berlin on 18 July 1906. It apparently was never ratified, but the border still follows the 1902–06 pillars.^[1]

Around Kilimanjaro that agreement replaced the 1886 wording with a chain of straight lines between hilltops: Latema Hill, the Schlobach Hills south of Lake Chala, Chala Hill and others. From there a long straight line runs northwest toward Lake Victoria.^[1] In the lake the line follows 1°S, except near the Mohuru Peninsula, where it keeps 1.5 km off the peninsula's southern tip.^[1]

From colonies to neighbours

Britain took control of the Kenya side through the British East Africa Company in 1888, and made it the East African Protectorate in 1895.^[1] The Tanzania side was German East Africa until the First World War. Britain then ran Tanganyika, first as a League of Nations mandate (a territory that one power ran on the League's behalf) and from 1946 as a UN trust territory.^[1] So from the end of the war until independence, Britain governed both sides of the line.^[1]

Tanganyika became independent on 21 December 1961 and Kenya on 12 December 1963. Tanganyika joined with Zanzibar in April 1964, and the country took the name Tanzania that October.^[1] In 1966 the US Geographer reported no known disputes about where the line runs.^[1]

People and crossings

People along the border are most concentrated near Lake Victoria, with smaller clusters at the foot of Kilimanjaro and on the coastal plain. Much of the land in between is national park or game reserve.^[1] The line divides the lands of the Maasai, one of East Africa's major peoples, as well as those of the Luo, Kuria, Digo and Segeju.^[1]

On 1 December 2018 Presidents John Magufuli of Tanzania and Uhuru Kenyatta of Kenya commissioned a one-stop border post at Namanga. The Holili/Taveta post was also operating by then.^[2]