Angola–Republic of the Congo border

[2] Portugal had begun exploring the coast of modern Angola in the 1480s, and over the following century established a number of coastal settlements, gradually expanding into the interior at the expense of the native kingdoms of Kongo, Matamba, Ndongo and others.

[3] Portugal had established a tentative presence in what is now Cabinda in 1783, a claim recognised in an Anglo-Portuguese treaty of 22 January 1815.

[3] In the 1880s numerous European powers sought to create colonies in the continent a process known as the Scramble for Africa; this culminated in the Berlin Conference of 1884, in which the European nations concerned agreed upon their respective territorial claims and the rules of engagements going forward.

[3] As a result, Portugal's claim to Cabinda was recognised, at the expense of Portugal's giving up a short section of coast to the Congo Free State of Belgian King Leopold II, thereby cutting off Cabinda from mainland Angola.

[2][3] France later amalgamated its central African territories into the federal colony of French Equatorial Africa (Afrique équatoriale française, AEF).