In many ways the Horn was close to the center of the mercantile world in 1500. It was not part of one empire. The dominant forces there were the Sultanate of Adal, the Swahili rulers of Mogadishu, and the Ethiopians and various tributaries of each. Adal had access to Afar and Somali cavalry, which was a powerful bonus, but soon they would have Ottoman assistance including gunpowder. Ethiopia would almost be extinguished by 1540, saved in part by Portugal. So gunpowder weapons were only entering use after 1500. Lightly armored, highly trained cavalry were the superweapons.

Ships working along the coast could make the long haul, and indeed came from as far as East Asia (or went there). Naval vessels weren't nearly so numerous or long legged, and in fact they relied on Ottoman and Egyptian forces to contest the Portuguese when it came down to it. Those vessels were not meant for blue water sailing, and lost badly. See Cippola's old Guns, Sails, and Empires, leavened with Lewis's history of Somalia and Marcus' s History of Ethiopia. Levtzion and Pouwels have chapters in their edited History of Islam in Africa that touch on these developments too.