North Yemen became independent of the Ottoman Empire in 1918 with Imam Yahya Muhammad creating the Mutawakkilite Kingdom of Yemen. In 1962, Northern Yemen became the Yemen Arab Republic. The British, who had set up a protectorate area around the southern port of Aden in the 19th century, withdrew in 1967 from what became then the People's Republic of South Yemen. On December 1st 1970 its name changed to the People's Democratic Republic of Yemen (PDRY). The two countries were formally unified as the Republic of Yemen in 1990. A southern secessionist movement in 1994 was subdued after a 2-month civil war.
Saudi Arabia and Yemen fixed their common borders by the Djedda Agreement, signed on the 13th of June 2000.