In October of 1886, European powers Britain and Germany sat down in Berlin to sign the Anglo-German Agreement. A subsequent ratification was done in 1890 and became known as the Heligoland treaty.
The latter treaty recognized the territory of the Sultan of Zanzibar as consisting of a mainland coastal strip ten miles inland stretching from Cape Delgado in the south to Kipini...
Thus Mount Kilimanjaro wasn’t hived off from Kenya, per se, as these were territories whose borders were being etched for the first time. The Germans also agreed to withdraw from Witu.