German rule was established quickly over Bagamoyo, Dar es Salaam, and Kilwa. The caravans of Tom von Prince, Wilhelm Langheld, Emin Pasha, and Charles Stokes were sent to dominate "the Street of Caravans." The Abushiri Revolt of 1888 was put down with British help the following year. In 1890, London and Berlin concluded the Heligoland-Zanzibar Treaty, which returned Heligoland to Germany and decided the border between GEA and the East Africa Protectorate controlled by Britain, although the exact boundaries remained unsurveyed until 1910.