During the Neolithic, the region was inhabited by Iberian tribes, who built religious and funerary monuments, megaliths, Dolmens and menhirs, which still survive in areas on the periphery of Lisbon. The Indo-European Celts invaded after the first millennium BC, mixing with the Pre-Indo-European population, giving a rise to Celtic-speaking local tribes such as the Cempsi.
Archaeological findings suggest that there was Phoenician influences dating back to the 1200 BC, leading some historians to believe that a Phoenician trading post might have occupied the centre of the present city (on the southern slope of the Castle hill). The sheltered harbour in the Tagus River estuary, was an ideal spot for a settlement and provided a secure port for provisioning of Phoenician ships travelling to the Islands of Tin (modern Isles of Scilly) and Cornwall. The new city might have been named Allis Ubbo, Phoenician for "safe harbour", according to one of several theories on the origin of Lisbon's toponymy. Another theory suggests that the settlement took the name of the pre-Roman word for the Tagus (Lisso or Lucio). The Tagus settlement was also an important output on commercial trade with inland tribes who collected valuable metals, salt, salted-fish, and the Lusitanian horses (that were renowned in antiquity). Although Phoenician remains from the 8th century BC were found beneath the Mediaeval Sé Cathedral, modern historians however, believe that Lisbon was an ancient autochthonous settlement (Roman oppidum) and that, at most, it maintained commercial relations with the Phoenicians (accounting Phoenician pottery and artefacts).
Lisbon's name was written Ulyssippo in Latin by the geographer Pomponius Mela, a native of Hispania. It was later referenced as "Olisippo" by Pliny the Elder, and to the Greeks as Olissipo (????????) and Olissipona (??????????). According to legend, the location was named for Ulysses, who founded the settlement after he left Troy to escape the Greek coalition. Later, the Greek name was corrupted in vulgar Latin to Olissipona.
Some of the native gods worshipped in Lisbon were Aracus, Carneus, Bandiarbariaicus, and Coniumbricenses.