|The ancient kingdom of Sheba, and its port of Aden, occupied a strategic location on the Arabian peninsula, allowing it to have dominated the trade routes that passed from Africa through the Middle East to India and back again. Islam came early to the region and in the 10th century, the Zaidi sect gave Yemen its kings (and, concurrently, its religious leaders). The Zaidis ruled until 1962. But control over Aden was disputed by many peoples including the Portuguese, the Ottomans, and the British. Britain made Aden a crown colony in 1839, with portions of the country becoming a protectorate. The Ottomans exerted control over the region twice: from the mid-16th to the mid-17th centuries and from 1849 to 1918; they were expelled only at the conclusion of World War I and Yemen became independent in 1918. All did not go smoothly, however, as conflict arose with the Saudis, who invaded in 1934, and with Britain in 1954 over Aden. The throne was challenged in 1955 and when the imam died in 1962, the country was divided into North and South. Shortly thereafter, Aden and the protectorate began agitating for independence. South Yemen declared independence in 1967. Its leftist regime was socialist in nature. The North, civil war continued between royalist and republican elements until 1970. Clashes between north and south occurred in the early '70s and in 1979, full-scale war was launched by the South. North and South were reunited in 1990.