The battle galley is a unique phenomenon that could exist only on the Mediterranean Sea. Although galleys could sometimes appear in the Atlantic, and in the Baltic there was a completely independent tradition of building galleys. The Mediterranean battle galley dates back to the battle trireme of the ancient Greeks and the bireme of the ancient Romans. Later, the design of the galley was significantly influenced by the Byzantine dromon, which appeared in the 5th century. All this was superimposed on the tradition of using the galley as a warship. In the Middle Ages, special types of galleys appeared in Italy and the Islamic east.