Yemen Arab Republic

The Yemen Arab Republic (YAR; الجمهورية العربية اليمنية al-Jumhūrīyah al-‘Arabīyah al-Yamanīyah), commonly known as North Yemen or Yemen (Sanaʽa), was a country that existed from 1962 to 1990 in the northwestern part of what is now Yemen. Its capital was at Sanaa. It united with the People's Democratic Republic of Yemen (commonly known as South Yemen) on 22 May 1990 to form the current Republic of Yemen.

History
Following the dissolution of the Ottoman Empire in 1918 after the First World War, northern Yemen became an independent state as the Mutawakkilite Kingdom of Yemen. On 26 September 1962, the North Yemeni republican revolutionaries inspired by the Arab nationalist ideology of the United Arab Republic (Egyptian) President Gamal Abdel Nasser deposed the newly crowned King Muhammad al-Badr, took control of Sanaʽa, and established the Yemen Arab Republic (YAR). This coup d'état marked the beginning of the North Yemen Civil War that pitted YAR troops, assisted by the United Arab Republic (Egypt), against Badr's royalist forces, supported by Saudi Arabia and Jordan. Conflict continued periodically until 1967, when Egyptian troops were withdrawn to join the conflict of the Six-Day War. By 1968, following a final royalist siege of Sanaa, most of the opposing leaders reached a reconciliation. Saudi Arabia recognized the Republic in 1970.

Unlike East and West Germany, North and South Korea or North and South Vietnam, the YAR and its southeastern neighbor, the People's Democratic Republic of Yemen (PDRY), also known as South Yemen, remained relatively cordial, though relations were often strained. Following the Yemenite War of 1972, the two nations declared that unification would eventually occur. However, these plans were put on hold due to the Yemenite War of 1979, and war was stopped only by an Arab League intervention. The goal of unity was reaffirmed by the northern and southern heads of state during a summit meeting in Kuwait in March 1979.

Unification
In May 1988, the YAR and PDRY governments came to an understanding that considerably reduced tensions. They agreed to renew discussions concerning unification, to establish a joint oil exploration area along their undefined border, to demilitarize the border, and to allow Yemenis unrestricted border passage on the basis of a national identification card.

Official Yemeni unification took place on 22 May 1990, with a planned, 30-month process, scheduled for completion in November 1992. The first stamp bearing the inscription "Yemen Republic" was issued in October 1990. While government ministries proceeded to merge, both currencies remained valid until 11 June 1996. A civil war in 1994 delayed the completion of the final merger.