Tartessus, ancient region and town of the Guadalquivir River valley in southwestern Spain, probably identical with the Tarshish mentioned in the Bible. It prospered from trade with the Phoenicians and Carthaginians but was probably destroyed by the latter about 500 bc.

Both Atlantis and Tartessos were believed to have been advanced societies which collapsed when their cities were lost beneath the waves; supposed further similarities with the legendary society make a connection seem feasible, though virtually nothing is known of Tartessos, not even its precise site.

Tartessos is now generally considered to be a civilisation that formed from a mixture of indigenous people and Greek and Phoenician colonisers in the Iberian Peninsula. And it was wealthy too, thanks to rich resources of metal and a prosperous trade economy.

Tartessos was a historical culture with a tangible presence in the archaeological and historical record, while Atlantis was a fictional construct created by Plato to illustrate philosophical concepts.