Lusitania has been inhabited since the Paleolithic period. Implements made by humans have been found at widely scattered sites. The Ice Ages did not touch Lusitania, and it was only after the disappearance of the Paleolithic hunting cultures that a warmer climate gave rise to a river-centered culture. At the end of the Paleolithic period, about 7000 B.C., the valley of the Tagus River (Portuguese, Rio Tejo) was populated by hunting and fishing tribes, who lived at the mouths of the river's tributaries. These people left huge kitchen middens containing the remains of shellfish and crustaceans, as well as the bones of oxen, deer, sheep, horses, pigs, wild dogs, badgers, and cats. Later, perhaps about 3000 B.C., Neolithic peoples constructed crude dwellings and began to practice agriculture. They used polished stone tools, made ceramics, and practiced a cult of the dead, building many funerary monuments called dolmens. By the end of the Neolithic period, about 2000 B.C., regions of cultural differentiation began to appear among the Stone Age inhabitants of the Iberian Peninsula, one of these being the western Megalithic culture. Present-day Portugal is thus rich in Megalithic neocropolises, the best known of which are at Palmela, Alcalar, Reguengos, and Monsaraz.

The Paleolithic and Neolithic periods were followed by the Bronze Age and the Iron Age (probably between 1500 and 1000 B.C.). During this time, the Iberian Peninsula was colonized by various peoples. One of the oldest were the Lígures, about whom little is known. Another were the Iberos, thought to have come from North Africa. The Iberos were a sedentary people who used a primitive plow, wheeled carts, had writing, and made offerings to the dead.

Data as of January 1993