Yemen's history: a union of two states contested since 1990

What the incense kingdoms built in the south

For more than two thousand years before Islam, the south-western corner of Arabia was held by a series of trading states whose income came from frankincense and myrrh, and from their access to spices from southern Asia and ivory and ostrich plumes from eastern Africa. Britannica names three that were known across the Mediterranean: the Minaean kingdom of Ma'in, the Sabaean kingdom of Saba, which is the biblical Sheba, and Himyar, which the Romans called the Homeritae. Their periods of power overlapped and ran, in Britannica's dating, from roughly 1200 BCE to 525 CE. The Yemen article on Wikipedia adds Qataban and Hadhramaut to the list of southern kingdoms.

Saba is the one whose works survive in the record. The Great Dam of Marib, upstream of the Sabaean capital, caught the run-off of the monsoon rains on the surrounding mountains and fed the fields around the city; the most reliable dating places it in about the 8th century BCE. UNESCO inscribed seven archaeological sites at Marib on the World Heritage List in 2023 as the Landmarks of the Ancient Kingdom of Saba, describing an administration that controlled much of the incense route across the peninsula and an irrigation system that made what UNESCO calls the largest man-made oasis of antiquity.

Rome reached the Red Sea in the 1st century CE. A Roman army under Aelius Gallus, 10,000 strong according to the Yemen article, was defeated before it reached Marib. The longer damage was commercial: once Roman traders learned where the luxury goods came from and how to sail the monsoon winds between Red Sea ports and India, Britannica writes, Yemen lost the revenue that kept its cities and waterworks in repair. The rupture of the Marib dam some time in the 6th century is the event Britannica treats as the symbolic end of the trading kingdoms.

Himyar unified the south by about 275, when Shammar Yahri'sh had conquered Hadhramaut, Najran and Tihamah. Its last kings were caught between faiths and empires. Dhu Nuwas, a convert to Judaism, carried out a massacre of the Christian population; an army from Aksum, in what is now Ethiopia, invaded and its commander Abraha stayed on to rule. The Himyarites then turned to Sasanian Persia to expel the Aksumites, and Yemen became a Persian satrapy whose last governor accepted Islam in 628, according to Britannica.

How Zaydi imams came to hold the highlands

Islam spread quickly. Muhammad sent his cousin Ali to Sanaa around 630, and the Great Mosque of Sanaa and the mosque at al-Janad near Taiz are thought to be among the earliest examples of Islamic architecture. Within two centuries the caliphs' governors were founding dynasties of their own: Muhammad ibn Ziyad made Zabid his capital around 818.

The event that shaped the next thousand years came in 893, when Yahya ibn al-Husayn, a cleric and judge, was invited from Medina to Saada to arbitrate between tribes. He brought the Zaydi branch of Shia Islam, which accepts Zayd ibn Ali as a legitimate successor in the line of the Prophet, and founded an imamate in 897 that the Hashid and Bakil tribes, later called "the twin wings of the imamate", came to accept. Britannica writes that much of Yemeni culture for the next thousand years bore the stamp of Zaydi Islam.

The lowlands and the south went their own way under a run of dynasties:

Zabid, capital of Yemen from the 13th to the 15th century in UNESCO's account, kept an Islamic university known across the Muslim world, and was inscribed as a World Heritage site in 1993.

How coffee drew the Ottomans back

Coffee brought the outside world back. Britannica dates the first drinking of it to about the beginning of the 15th century, among Sufis, and from the 16th century the Egyptians, the Ottomans and several European powers fought over the Red Sea trade it opened. The Ottomans took Aden in 1538 and Zabid in 1539, but held the coast more than the mountains. Zaydi imams of the Qasimi line drove them out in the 17th century, and under al-Mutawakkil Isma'il, who succeeded in 1644, the imamate ruled the whole of Yemen while it was, in the Yemen article's words, the sole coffee producer in the world.

The monopoly lasted until European traders smuggled coffee plants out and grew them in colonies in Asia, Africa and the Americas in the first half of the 18th century. Britannica records what that did to the ports: Aden and Mocha, each once home to more than 10,000 people, shrank to villages of a few hundred.

Why two empires drew a line across Yemen

The modern division of Yemen was made by outsiders over the 19th century. The East India Company wanted a coaling station between Suez and Bombay, and Britain took Aden from the Sultan of Lahej in 1839. The Ottomans returned to the Tihamah coast in 1849 after two centuries away, and the opening of the Suez Canal in 1869 settled their decision to stay; by 1873 they held the northern highlands and governed from Sanaa.

As the Ottomans pushed inland to Sanaa and Taiz, the British signed protection treaties with more than a dozen of the small states around Aden, which Britannica reads as a buffer for the port more than an ambition to rule the interior. Clashes along the unmarked frontier led to a joint survey in 1904 and a treaty that fixed the line between Ottoman North Yemen and the British possessions in the south. Both Yemens would later regard that treaty as foreign interference in their affairs.

How an imam ruled the independent north

Imam Yahya Hamid al-Din led a revolt from 1904, and a treaty of 1911 recognised him as autonomous ruler of the Zaydi highlands. When the Ottoman forces left at the end of the First World War in 1918, he became ruler of an independent north, the Mutawakkilite Kingdom of Yemen, and claimed a "historic Yemen" that included Aden, the protectorates and the provinces of Asir, Najran and Jizan to the north. A war with Saudi Arabia in 1934 ended in the Treaty of Taif on 14 June 1934, which left Najran, Asir and Jizan on the Saudi side. In the same year he signed a treaty with Britain promising not to attack Aden.

In the south, Britain kept consolidating. The diplomat Harold Ingrams negotiated a truce among more than 1,400 tribes and clans in the Hadhramaut, which brought its great valley into the protectorate system, and Aden grew into a port of emigrants from India, East Africa and South-East Asia.

How two republics replaced an imam and a colony

Dissatisfaction with Yahya spread through reformers, part of the traditional elite and some of the religious scholars, and he was assassinated in a coup in early 1948. His son Ahmad rallied the northern tribes, overthrew the plotters and ruled much as his father had. He died in September 1962; within a week army officers deposed his son Muhammad al-Badr and declared the Yemen Arab Republic.

Who fought the civil war in the north

The imam escaped to the northern highlands and raised the tribes, and a civil war followed that lasted until 1970. Egypt sent troops and equipment to defend the republic; Saudi Arabia gave the royalists aid and sanctuary, and Britannica lists Iran and Jordan among their backers and the Soviet bloc among the republic's. A compromise in 1970, made with the blessing of Egypt and Saudi Arabia, kept the republic, gave royalists some posts and barred the imam's family from returning. Britannica traces a later Zaydi revivalist movement partly to the loss of standing that followed.

How Aden won its independence

The revolution in the north encouraged the movements against British rule in the south. Britain had folded all but four of the 21 protectorate states into the Federation of South Arabia by 1965, with Aden inside it, and announced that it would leave by 1968. The armed campaign known as the Aden Emergency began on 14 October 1963 with an attack by tribesmen from Radfan; the British declared the state of emergency after a grenade attack at Khormaksar airport on 10 December 1963. By late 1967 the National Liberation Front had the upper hand over its rival, FLOSY, and Britain transferred sovereignty to it on 30 November 1967.

The People's Republic of South Yemen moved towards the Soviet Union for aid and on 30 November 1970 renamed itself the People's Democratic Republic of Yemen, with a Marxist programme of nationalisation and one legal party, which became the Yemeni Socialist Party. The two states fought brief border wars in 1972 and 1979, each followed by an agreement to unify that came to nothing. In the north Ali Abdullah Saleh became president in 1978 after two predecessors were assassinated within eight months; in the south a power struggle in January 1986 killed thousands, among them the former leader Abd al-Fattah Ismail.

Why unification held for only four years

Two things made union possible, in Britannica's reading: oil and gas found at about the same time in the border region running from Marib to Shabwah, and the end of the Soviet support that South Yemen depended on. The two ruling parties agreed in late November 1989 to merge, and the legislatures of both states adopted a single constitution on 22 May 1990, the day the Republic of Yemen came into being. Sanaa became the political capital and Aden the economic one, Saleh was president, and the southern leader Ali Salim al-Beidh vice president.

The Gulf crisis broke the economy within months. Yemen, a member of the UN Security Council for 1990 and 1991, refused to join the coalition against Iraq after the invasion of Kuwait. Saudi Arabia cut its aid and expelled Yemeni workers: several hundred thousand in Britannica's account, 800,000 in 1990 and 1991 in the Yemen article's. The first elections of the united state, in April 1993, gave Saleh's General People's Congress a large plurality of seats, with the Islamist Islah party and the Yemeni Socialist Party in strong minorities, and international monitors judged them relatively free and fair.

The partnership did not last. Al-Beidh withdrew to Aden in August 1993; an accord signed in Amman on 20 February 1994 could not hold, and on the night of 21 May 1994 he declared a separate Democratic Republic of Yemen. Northern forces defeated the south by early July. Parliament re-elected Saleh on 1 October 1994, after the plural executive of the transition was abolished. In 1999 he won the country's first direct presidential election with 96% of the vote. In the same years Yemen settled two frontiers: an arbitration panel awarded most of the Hanish Islands to Yemen against Eritrea in 1998, and a final border agreement with Saudi Arabia was signed in June 2000.

Where the northern rebellion and southern protest began

Two movements that would later fight the state grew in the 2000s. In the north, the Zaydi activist and former member of parliament Hussein Badr al-Din al-Houthi built a youth network, the Believing Youth, which the government funded until 2000. Opposition to Saleh's support for the United States after 2001 turned it into a movement, and in June 2004 the government moved against it; Hussein al-Houthi was killed by government forces that September. The government said the Houthis were trying to overthrow it and impose Shia law; the rebels said they were defending themselves against persecution and attack, according to the Yemen article. The fighting recurred for years.

In the south, protests began in 2007 among retired officers over forced retirements and pensions and spread to civil servants, lawyers, teachers and the unemployed, who accused the government of discriminating against the south since 1994. Some of them, Britannica writes, began to question the union itself.

The Arab uprisings of 2011 reached Sanaa in late January. On 18 March 2011 gunmen loyal to Saleh fired on protesters in Sanaa and killed at least 50 people, and senior officers defected to the opposition. Saleh was wounded in a bomb attack on the presidential palace on 3 June 2011, and on 23 November 2011 he signed a Gulf Cooperation Council plan in Riyadh that transferred his powers to his deputy, Abd Rabbuh Mansur Hadi, in return for immunity. Hadi was the only candidate in the election of February 2012.

How the Houthis took Sanaa and the war began

Cuts to fuel subsidies in July 2014 brought renewed protests; in late September 2014 Houthi fighters took control of Sanaa. In January 2015 they took the presidential palace and Hadi resigned. On 6 February 2015 the Houthis dissolved parliament and issued a "constitutional declaration" naming a Revolutionary Committee as the interim authority, which the Yemen article records as rejected by opposition politicians, foreign governments and the United Nations; Abdul-Malik al-Houthi called the takeover a "glorious revolution". Hadi escaped to Aden on 21 February 2015, withdrew his resignation and called for recognition as the constitutional president.

On 26 March 2015 Saudi Arabia announced Operation Decisive Storm and began air strikes at the head of a coalition, saying the Houthis were being aided by Iran. Britannica writes that Iran's Quds Force supplied the movement's weapons and training as its attacks grew more sophisticated; the Houthis and the Iranian government have denied any military affiliation, according to the Wikipedia article on the movement. Saleh, who had backed the Houthis since May 2015, broke with them in late 2017 and was killed near Sanaa on 4 December 2017.

Where the front lines settled after the intervention

Pro-Hadi forces retook Aden in July 2015 with coalition support, and the Houthis were driven from most of the south but kept Sanaa and the north. Southern separatists backed by the United Arab Emirates seized Aden in January 2018, and in 2017 had formed the Southern Transitional Council, which declared self-rule in April 2020 and took Socotra that June. A ceasefire was agreed for the port of Hodeidah in December 2018. A truce that began in April 2022 was renewed twice and formally lapsed that October, though fighting stayed low; the same month it began, Hadi handed his powers to a Presidential Leadership Council.

The United Nations estimated 377,000 deaths in the war by the beginning of 2022, 60% of them from indirect causes such as hunger and the lack of health care, according to the Council on Foreign Relations, which also reports more than twenty-five thousand coalition air strikes and more than nineteen thousand civilian casualties from them.

What followed the attacks on Red Sea shipping

After the Hamas attack on Israel on 7 October 2023, the Houthis fired missiles and drones towards Israel and attacked shipping off Yemen, which the Yemen article describes as an act of solidarity with the Palestinians. The United States and the United Kingdom struck Houthi targets in January 2024, and the United States reached a ceasefire with the Houthis in May 2025. In December 2025 the Southern Transitional Council tried to take Hadhramaut and al-Mahra from the government; a counter-offensive with Saudi support defeated it, and Britannica records that it was formally disbanded in January 2026 and that the Emirates withdrew its forces, including from Socotra. In September 2026 the Houthis took Mokha, the town of Dhubab and Perim Island on the Bab el-Mandeb Strait, and a World Health Organization report cited by the Council on Foreign Relations reported on 28 September 2026 put the deaths from the renewed fighting at more than eight hundred.