Aden ( , ; Yemeni pronunciation: ) is a seaport city in Yemen, located by the eastern approach to the Red Sea (the Gulf of Aden), some east of Bab-el-Mandeb. Its population is approximately 800,000 people. Aden's ancient, natural harbour lies in the crater of a dormant volcano which now forms a peninsula, joined to the mainland by a low isthmus. This harbour, Front Bay, was first used by the ancient Kingdom of Awsan between the 5th and 7th centuries BC. The modern harbour is on the other side of the peninsula. Aden gives its name to the Gulf of Aden.