Yemen is in the southwest corner of the Arabian Peninsula, bordered on the west by the Red Sea, on the north by Saudi Arabia, and on the south by the former Aden Protectorates, where the majority of the Jewish population lived. (Aden was occupied by the British in 1839, became a crown colony in 1937, and in 1967 became the state of South Yemen, merging in 1990 with what was then called North Yemen. This discussion relates only to North Yemen.) Yemen has three distinct geographical regions: the hot coastal strip; the interior highlands, which are characterized by numerous narrow fertile valleys and rugged peaks that form natural boundaries separating parts of the population from one another and from any effective central control; and the arid eastern foothills, which lead to the Rub' al-Khali desert of the central Arabian Peninsula.
The Jews were Yemen's only non-Muslim minority, and they lived among a population almost evenly divided between the Shafici Sunnis, members of mainstream Islam, and the Zaydis, members of one branch of the Shiites whose adherents believe that as the descendants of Ali, the cousin and sonin-law of the prophet Muhammad, they have the sole prerogative to lead the Muslim community. Unlike other Shiite sects, religious differences between the Sunnis and the Zaydis in matters of doctrine and law are relatively insignificant. Yemen has been under Zaydi domination since the sixteenth century, headed by Zaydi imams who were acknowledged as political and religious leaders.
During the nineteenth century internal instability characterized Yemen. In addition, because of its strategic location international interest in the affairs of the country was growing: Yemen had long been an essential link in the land-and-seagoing trade network of the Mediterranean, the Red Sea and