Yemen was one of the oldest centers of civilization in the Near East. Between the 12th century BC and the 6th century AD, it was part of the Minaean, Sabaean, and Himyarite kingdoms, which controlled the lucrative spice trade, and later came under Ethiopian and Persian rule. In the 7th century, Islamic caliphs began to exert control over the area. After this caliphate broke up, the former north Yemen came under control of Imams of various dynasties usually of the Zaidi sect, who established a theocratic political structure that survived until modern times. (Imam is a religious term. The Shiites apply it to the prophet Muhammad's son-in-law Ali, his sons Hasan and Hussein, and subsequent lineal descendants, whom they consider to have been divinely ordained unclassified successors of the prophet.)

Egyptian Sunni caliphs occupied much of north Yemen throughout the 11th century. By the 16th century and again in the 19th century, north Yemen was part of the Ottoman empire and in some periods its Imams exerted suzerainty over south Yemen.

Former North Yemen

Ottoman government control was largely confined to cities with the Imam's suzerainty over tribal areas formally recognized. Turkish forces withdrew in 1918, and Imam Yahya strengthened his control over north Yemen. Yemen became a member of the Arab league in 1945 and the United Nations in 1947.

Imam Yahya died during an unsuccessful coup attempt in 1948 and was succeeded by his son Ahmad, who ruled until his death in September 1962. Imam Ahmad's reign was marked by growing repression, renewed friction with the United Kingdom over the British presence in the south, and growing pressures to support the Arab nationalist objectives of Egyptian President Jamal Abdul Nasser.

Shortly after assuming power in 1962, Ahmad's son, Badr, was deposed by revolutionary forces which took control of Sanaa and created the Yemen Arab Republic (YAR). Egypt assisted the YAR with troops and supplies to combat forces loyal to the Imamate. Saudi Arabia and Jordan supported Badr's royalist forces to oppose the newly formed republic. Conflict continued periodically until 1967 when Egyptian troops were withdrawn. By 1968, following a final royalist siege of Sanaa, most of the opposing leaders reached a reconciliation; Saudi Arabia recognized the Republic in 1970.

Former South Yemen

British influence increased in the south and eastern portion of Yemen after the British captured the port of Aden in 1839. It was ruled as part of British India until 1937, when Aden was made a crown colony with the remaining land designated as east Aden and west Aden protectorates. By 1965, most of the tribal states within the protectorates and the Aden colony proper had joined to form the British-sponsored federation of south Arabia.

In 1965, two rival nationalist groups--the Front for the Liberation of Occupied South Yemen (FLOSY) and the National Liberation Front (NLF)--turned to terrorism in their struggle to control the country. In 1967, in the face of uncontrollable violence, British troops began withdrawing, federation rule collapsed, and NLF elements took control after eliminating their FLOSY rivals. South Arabia, including Aden, was declared independent on November 30, 1967, and was renamed the People's Republic of South Yemen. In June 1969, a radical wing of the Marxist NLF gained power and changed the country's name on December 1, 1970, to the People's Democratic Republic of Yemen (PDRY). In the PDRY, all political parties were amalgamated into the Yemeni Socialist Party (YSP), which became the only legal party. The PDRY established close ties with the Soviet Union, China, Cuba, and radical Palestinians.

Republic of Yemen

In 1972, the governments of the PDRY and the YAR declared that they approved a future union. However, little progress was made toward unification and relations were often strained. In 1979, simmering tensions led to fighting, which was only resolved after Arab League mediation. The goal of unity was reaffirmed by the northern and southern heads of state during a summit meeting in Kuwait in March 1979. However, that same year the PDRY began sponsoring an insurgency against the YAR. In April 1980, PDRY President Abdul Fattah Ismail resigned and went into exile. His successor, Ali Nasir Muhammad, took a less interventionist stance toward both the YAR and neighboring Oman. On January 13, 1986, a violent struggle began in Aden between Ali Nasir Muhammad and the returned Abdul Fattah Ismail and their supporters. Fighting lasted for more than a month and resulted in thousands of casualties, Ali Nasir's ouster, and Ismail's death. Some 60,000 persons, including Ali Nasir and his supporters, fled to the YAR.

In May 1988, the YAR and PDRY governments came to an understanding that considerably reduced tensions including agreement 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 only a national identification card.

In November 1989, the leaders of the YAR (Ali Abdallah Salih) and the PDRY (Ali Salim Al-Bidh) agreed on a draft unity constitution originally drawn up in 1981. The Republic of Yemen (ROY) was declared on May 22, 1990. Ali Abdallah Salih became President and Ali Salim Al-Bidh became Vice President.

A 30-month transitional period for completing the unification of the two political and economic systems was set. A presidential council was jointly elected by the 26-member YAR advisory council and the 17-member PDRY presidium. The presidential council appointed a Prime Minister, who formed a Cabinet. There was also a 301-seat provisional unified Parliament, consisting of 159 members from the north, 111 members from the south, and 31 independent "at-large" members appointed by the chairman of the council.

A unity constitution was agreed upon in May 1990 and ratified by the populace in May 1991. It affirmed Yemen's commitment to free elections, a multi-party political system, the right to own private property, equality under the law, and respect of basic human rights. Parliamentary elections were held on April 27, 1993. International groups assisted in the organization of the elections and observed actual balloting. The resulting Parliament included 143 GPC, 69 YSP, 63 Islaah (Yemeni grouping for reform, a party composed of various tribal and religious groups), 6 Baathis, 3 Nasserists, 2 Al Haq, and 15 independents. The head of Islaah, Paramount Hashid Sheik Abdallah Bin Husayn Al-Ahmar, is the speaker of Parliament.

Islaah was invited into the ruling coalition, and the presidential council was altered to include one Islaah member. Conflicts within the coalition resulted in the self-imposed exile of Vice President Ali Salim Al-Bidh to Aden beginning in August 1993 and a deterioration in the general security situation as political rivals settled scores and tribal elements took advantage of the unsettled situation. Haydar Abu Bakr Al-Attas (former southern Prime Minister) continued to serve as the ROY Prime Minister, but his government was ineffective due to political infighting. Continuous negotiations between northern and southern leaders resulted in the signing of the document of pledge and accord in Amman, Jordan on February 20, 1994. Despite this, clashes intensified until civil war broke out in early May 1994.

Almost all of the actual fighting in the 1994 civil war occurred in the southern part of the country despite air and missile attacks against cities and major installations in the north. Southerners sought support from neighboring states and received billions of dollars of equipment and financial assistance. The United States strongly supported Yemeni unity, but repeatedly called for a cease-fire and a return to the negotiating table. Various attempts, including by a UN special envoy, were unsuccessful to effect a cease-fire. Southern leaders declared secession and the establishment of the Democratic Republic of Yemen (DRY) on May 21, 1994, but the DRY was not recognized by the international community. Ali Nasir Muhammad supporters greatly assisted military operations against the secessionists and Aden was captured on July 7, 1994. Other resistance quickly collapsed and thousands of southern leaders and military went into exile.

Early during the fighting, President Ali Abdallah Salih announced a general amnesty which applied to everyone except a list of 16 persons. Most southerners returned to Yemen after a short exile.

An armed opposition was announced from Saudi Arabia, but no significant incidents within Yemen materialized. The government prepared legal cases against four southern leaders (Ali Salim Al- Bidh, Haydar Abu Bakr Al-Attas, Abd Al-Rahman Ali Al-Jifri, and Salih Munassar Al-Siyali) for misappropriation of official funds. Others on the list of 16 were told informally they could return to take advantage of the amnesty, but most remained outside Yemen. Although many of Ali Nasir Muhammad's followers were appointed to senior governmental positions (including Vice President, Chief of Staff, and Governor of Aden), Ali Nasir Muhammad himself remained abroad in Syria. In the aftermath of the civil war, YSP leaders within Yemen reorganized the party and elected a new politburo in July 1994. However, the party remained disheartened and without its former influence. Islaah held a party convention in September 1994. The GPC did the same in June 1995.

In 1994, amendments to the unity constitution eliminated the presidential council. President Ali Abdallah Salih was elected by Parliament on October 1, 1994 to a five-year term. The constitution provides that henceforth the President will be elected by popular vote from at least two candidates selected by the legislature.

The chief incense traders were the Minaeans, who established their capital Karna (now known as Sadah), before they were superseded by the Sabaeans in 950 BC. 

The Sabaean capital was Marib, where a large temple was built.  The mighty Sabaean civilization endured for about 14 centuries and was based not only on the spice trade, but also on agriculture.  The impressive dam, built at Marib in the 8th century, provided irrigation for farmland and stood for over a millennium.  Some Sabaean carved inscriptions from this period are still extant.

The Himyarites established their capital at Dhafar (now just a small village in the Ibb region), and gradually absorbed the Sabaean kingdom.  They were culturally inferior to the Sabaeans and traded from the port of al-Muza on the Red Sea.  By the first century BC, the Romans had conquered the area.