Anglo-French Convention of 1889

The Anglo-French Convention of 1889 was a diplomatic agreement signed on August 10, 1889, between Great Britain and France, that delimited parts of their colonial boundaries in West Africa, notably between the British territory of the Gambia and the French colony of Senegal, and between Britain’s Lagos Colony and French Dahomey. The Senegambian border was set at ten kilometers north and south of the river as far inland as Yarbutenda (near modern-day Koina, The Gambia), with a 10 km radius to mark the eastern border measured from the center of town.

Source: Wikipedia — Anglo-French Convention of 1889 (CC BY-SA 4.0)