Lazica, situated on the eastern shore of the Black Sea, and controlling important mountain passes across the Caucasus and to the Caspian Sea, had a key strategic importance for both empires. For Byzantines, it was a barrier against a Persian advance through Iberia to the coasts of the Black Sea. Persians on the other side hoped to gain access to the sea, and control a territory from which Iberia, which was by now under their firm domination, could be threatened.[3]