 Surrounded by huge walls, defenses erected by the Romans at the height of their power, and defended by armies of Germanic mercenaries, Constantinople ended up surviving as a city virtually besieged for the greater part of its life, its territories eventually restricted to the direct area of the city.The Ghassanids were Arab Christians that emigrated from Yemen to the Hauran, in southern Syria.The term Ghassan refers to the kingdom of the Ghassanids, and supposedly means "a spring of water".