The history of Portugal can be traced from circa 400,000 years ago, when the region of present-day Portugal was inhabited by Homo heidelbergensis. The oldest human fossil is the skull discovered in the Cave of Aroeira in Almonda. Later Neanderthals roamed the northern Iberian peninsula. Homo sapiens arrived in Portugal around 35,000 years ago.
Pre-Celtic tribes such as Lusitanians, Turduli and Oestriminis lived in the centre and north. In the south the Cynetes lived in the Algarve and Lower Alentejo regions before the 6th century BC, developed the city of Tartessos and the written Tartessian language, and left many stelae in the south of the country. Early in the first millennium BC, waves of Celts from Central Europe invaded and intermarried with the local populations to form several ethnic groups and many tribes. Their presence is traceable, in broad outline, through archaeological and linguistic evidence. They dominated the northern and central area, while the south retained much of its Tartessian character, combined with the Celtici until the Roman conquest. Some small, semi-permanent trading settlements were founded by Phoenician-Carthaginians on the southern coast of the Algarve.