Eritrea formed part of the ancient Ethiopian kingdom of Aksum until the 7th cent. Thereafter Ethiopian emperors maintained an intermittent presence in the area until the mid-16th cent., when the Ottoman Empire gained control of much of the coastal region. Beginning in the mid-19th cent. Ethiopia struggled against Egypt and Italy for control of Eritrea. In the 1880s, Italy occupied the coastal areas around Aseb and Massawa, and by 1890 had extended its territory enough to proclaim the colony of Eritrea (named after the Roman term for the Red Sea, Mare erythraeum ). The colony was later the main base for Italy's conquest (1935–36) of Ethiopia.
In World War II, Eritrea was captured (1941) by the British. Ethiopia had long demanded control of Eritrea on the ground of ethnic affinity, but Britain occupied Eritrea after the war and, beginning in 1949, administered it as a UN trust territory. In 1950 the United Nations decided that Eritrea was to be made independent as a federated part of Ethiopia, and in late 1952 this decision became effective. In late 1962 the Eritrean assembly voted to end the federal status and to unify Eritrea with Ethiopia. After 1962, Eritreans who opposed union carried on sporadic guerrilla warfare against Ethiopia and the Eritrean Liberation Front (ELF) was founded. In the 1970s a rival insurgent group, the Eritrean Popular Liberation Forces (EPLF), was formed and battled the ELF for supremacy.
After Emperor Haile Selassie's overthrow in a military coup in 1974, the two insurgent groups united to fight against the Ethiopian government's forces. Fighting increased and by 1976 the Eritreans had virtually forced the government forces out of the province. However, the Ethiopian government, with massive amounts of aid and troops from the USSR and Cuba, was able to defeat the Eritreans in 1978. After their defeat the insurgents were forced to return to sporadic guerrilla warfare. During the 1980s the rebels continued their attacks on Ethiopian troops and eventually Eritreans controlled most of the countryside.
In 1991 the insurgents succeeded in capturing Asmara and the ports, giving them control of the province. That same year the United Nations scheduled a referendum on Eritrean independence. In 1993, after 30 years of warfare and the death of an estimated 200,000, Eritreans overwhelmingly voted for independence, and Isaias Afwerki, formerly the principal leader of the EPLF, became the new nation's first president. His party, renamed the People's Front for Democracy and Justice (PFDJ), became the only viable political organization. The new government enacted legislation to promote trade and investment and provide for the privatization of many state firms.
In the mid-1990s, Eritrean and Yemeni forces clashed over control of the Hanish and other island groups in the Red Sea; the dispute was resolved in 1998, largely in Yemen's favor. A border war between Ethiopia and Eritrea broke out in 1998 when Eritrean forces occupied disputed territory. Fighting was largely inconclusive, with many thousands killed on both sides, until May, 2000, when Ethiopian forces launched a major offensive, securing the disputed territory and driving further into Eritrea. A cease-fire agreement signed in June called for a truce, the establishment of a 15.5 mi (9.6 km) UN-patrolled buffer zone (in Eritrean territory), and the demarcation of the border by UN cartographers. The war hampered Eritrea's efforts to rebuild its economy and made the previously self-reliant young nation dependent on foreign aid to feed its citizens. An estimated 70,000 to 120,000 Eritrean and Ethiopian soldiers and civilians died in the conflict.
Peacekeeping forces arrived in significant numbers by Dec., 2000, and there was steady, if sometimes fitful, progress towards the goals of the cease-fire agreement in 2001. Late in the 2001 the government arrested a number of opposition leaders and journalists and closed private newspapers; elections scheduled for that December were indefinitely postponed. In Apr., 2002, the Hague Tribunal issued a complex ruling on the disputed border that favored Eritrea in some locations and Ethiopia in others. Ethiopian resistance subsequently delayed finalization of the border, and Eritrea refused to enter into discussions with Ethiopia.
Four years of drought led to a food crisis in Eritrea by 2002, requiring substantial international assistance, and conditions have not improved significantly since then. The political and human rights situation in the country also deteriorated; in 2004 Amnesty International accused Eritrea of persecuting religious minorities, using torture, and detaining thousands for criticizing the government. When those charges were reiterated in 2013, Amnesty International accused the government of having jailed some 10,000 people for political reasons.
Tensions with Ethiopia escalated in 2005 as both nations bolstered their forces along the disputed border. Frustrated with lack of progress on the border issue, Eritrea restricted UN peacekeepers movements in October. In November the United Nations called for Eritrea and Ethiopia to reduce their forces along the border and for Eritrea to end restrictions on UN forces, and expressed concern over Ethiopia's failure to finalize the border; UN sanctions were threatened for noncompliance. Eritrea rejected the ultimatum and in Dec., 2005, forced those UN forces from the United States, Canada, Europe, and Russia to withdraw. The same month, a Permanent Court of Arbitration claims commission ruled that Eritrea had violated international law in attacking Ethiopia, and that Ethiopia was entitled to compensation.
In Mar., 2006, Eritrea, apparently as a result of its continuing frustration with the border situation and the international community's response, expelled a number of foreign aid organizations despite the country's need for food aid. In response to Eritrea's restrictions on UN forces, the Security Council voted (May, 2006) to reduce UN forces on the border by a third. Relations between the UN peacekeepers and Eritrea continued to be extremely strained.
In Nov., 2006, the boundary commission responsible for demarcating the disputed border with Ethiopia said it would demarcate the border on maps, and that the Eritrea and Ethiopia would have a year to demarcate it on the ground. The 2007 deadline passed with issue unresolved. Meanwhile, in Dec., 2006, Ethiopia accused Eritrea of having soldiers in Somalia in support of Islamists there, saying that Eritrean dead had been found after the Islamists were routed. Eritrea denied the charges, but it was widely believed to have supplied the Islamists with arms. Eritrea subsequently sponsored an anti-Ethiopian, anti-Somali coalition that included Ethiopian rebels, Somali Islamists, and former members of the Somali government. Eritrea was again accused of aiding Somali Islamists in 2009; Eritrea's denials were undercut by public statements by Sheikh Hassan Dahir Aweys, an Islamist leader, that his group received Eritrean support.
In early 2008, after a prolonged cutoff of fuel supplies by Eritrea, UN forces were withdrawn from the country. In July, 2008, the Security Council voted to end the UN peacekeeping mission, blaming both Eritrea and Ethiopia for the failure of the mission, and all peacekeepers were withdrawn from the two nations by October.
Meanwhile, in June fighting erupted briefly between Eritrea and Djibouti near the Bab el Mandeb strait; Djibouti had accused Eritrea of occupying Djiboutian territory there earlier in the year. The United Nations called for both nations to withdraw from the disputed territory; when Eritrea did not, the Security Council unanimously called (Jan., 2009) for Eritrea to withdraw. In Aug., 2009, the Permanent Court of Arbitration claims commission issued its final war damages awards, calling for Eritrea to pay roughly $174 million to Ethiopia and Ethiopia $164 million to Eritrea. The Security Council imposed sanctions on Eritrea in Dec., 2009, for its support of Somalia's rebels and for refusing to withdraw from the disputed territory on the Djibouti border. In June, 2010, following the signing of an agreement that called for Qatar's emir to mediate between Eritrea and Djibouti, Eritrea withdrew its forces from disputed areas they had occupied. Additional UN sanctions were imposed in Dec., 2011, for supporting Somali rebels. In Mar., 2012, Ethiopia attacked what it described as several Eritrean military bases that were used to train Ethiopian antigovernment groups. A group of soldiers apparently mounted a coup attempt in Jan., 2013, but it quickly failed.