The Phoenicians founded colonies on the coast of Tripolitania, which were conquered by Carthage in the 6th century bc. Greeks subsequently established settlements in Cyrenaica. The Greek historian Herodotus, writing in the 5th century bc, described the Garamantes people of the Fezzan, who were sedentary farmers and used horse-drawn chariots in warfare. His account has been verified in the 20th century by ancient cave art, discovered in the Jabal Akakus (jabal means “mountains”) of the western Fezzan and the Jabal al ‘Uwaynat near the Egyptian border. Libya later became a Roman possession, until it was conquered by the Vandals in ad 455. After a reconquest by Byzantium in the following century, the region was won by the Arabs under Amr ibn al-As in 643.

The present borders of Libya contain a huge territory the size of the U.S. states of Texas, Oklahoma, Louisiana, and Mississippi combined. Largely desert with some limited potential for urban and sedentary life in its northwestern and northeastern corners, Libya has never been populous nor a power centre. Like its neighbour Algeria, Libya's very name is a neologism, created by the conquering Italians early in the 20th century. Like Algeria, much of Libya's earlier history—not only in the Islamic period but even before—reveals that both the western and eastern provinces were more closely linked with neighbouring territory, with Tunisia and Egypt respectively. Even during most of the Ottoman times the country was divided into two parts, one linked to Tripoli in the west and the other to Banghazi in the east.

Under Qaddafi’s leadership Libya took a much more active role not only in Arab affairs but also in international politics. Opposing the peace initiative toward Israel of Egyptian president Anwar al-Sadat, Libya took a leading part, along with Syria, in the so-called rejectionist front in 1978. Its support for the Palestine Liberation Organization later expanded to barely concealed subsidies for terrorists in other nations, and in the early 1980s the regime was believed to be linked to a campaign of assassinations directed against Libyan dissidents residing abroad. During this same period, Libyan forces intervened in a civil war in neighboring Chad. A peace treaty with Chad was signed in 1989. Libyan relations with the United States deteriorated in the early 1980s. In 1981 two Libyan fighter planes were shot down by U.S. Navy jets over the Gulf of Sidra, which Libya claimed as territorial waters. In 1982 the United States imposed an embargo on Libyan oil imports. Another encounter in the Gulf of Sidra in March 1986 resulted in the destruction of two Libyan ships by U.S. Navy ships.