Tartessos or Tartessus is assumed by most commentators to be identical with the wealthy city of Tarshish that is mentioned in the Bible. There have been persistent attempts over the past century to link Tartessos with Atlantis. The last king of Tartessia, in what is now Southern Spain, is noted by Herodotus to have been Arganthonios, who is claimed to have ruled from 630 BC until 550 BC. However, if these dates are only approximately true, then Atlantis cannot be identified with Tartessos as they nearly coincide with the lifetime of Solon, who received the story of Atlantis as being very ancient.
The existence of a ‘Tartessian’ empire is receiving gradual acceptance. Strabo writes of their system of canals running from the Guadalquivir River and a culture that had written records dating back 6,000 years. Their alphabet was slightly different to the ‘Iberian’. The Carthaginians were said to have been captured Tartessos after the reign of Arganthonios.
The exact location of this city is not known apart from being near the mouth of the Guadalquivir River in Andalusia. The Guadalquivir was known as Baetis by the Romans and Tartessos to the Greeks. The present day Gulf of Cadiz was known as Tartessius Sinus (Gulf of Tartessus) in Roman times. Cadiz is accepted to be a corruption of Gades that in turn is believed to have been named to after Gaderius.

The German archaeologist Adolf Schulten spent many years searching unsuccessfully for Tartessos, in the region of the Guadalquivir. He believed that Tartessos had been the centre of an ancient culture that was Atlantis or at least one of its colonies. Schulten also noted that Tartessos disappeared from historical records around 500 BC, which is after Solon’s visit to Egypt and so could not have been Atlantis.
Otto Jessen also believed that there had been a connection between Atlantis and Tartessos. Jean Gattefosse was convinced that the Pillars of Heracles were at Tartessos, which he identifies as modern Seville. However, Mrs E. M. Whishaw, who studied in the area for 25 years at the beginning of the 20th century, believed that Tartessos was just a colony of Atlantis. The discovery of a ‘sun temple’ 8 meters under the streets of Seville led Mrs Whishaw to surmise[053] that Tartessos may be buried under that city. Edwin Björkman wrote a short book,The Search for Atlantis[181] in which he identified Atlantis with Tartessos and also Homer’s Scheria.
More recently Karl Jürgen Hepke has written at length, on his website(a), about Tartessos. Dr. Rainer W. Kühne, following the work of another German, Werner Wickboldt, had an article[429] published in Antiquity that highlighted satellite images of the Guadalquivir valley that he has identified as a possible location for Atlantis. Kühne published an article(b) outlining his reasons for identifying Tartessos as the model for Plato’s Atlantis.
It was reported(c) in January 2010 that researchers were investigating the site in the Doñana National Park, at the mouth of the Guadalquivir, identified by Dr. Kühne as Atlantis. In 2011, Professor Richard Freund of the University of Hartford garnered a lot of publicity when he visited the site and expressed the view that it was the location of Tartessos which he equates with Atlantis.
A minority view is that Tarshish is related to Tarxien (Tarshin) in Malta, which, however, is located some miles inland.
A recent novel by C. E. Albertson[013] uses the idea of an Atlantean Tartessos as a backdrop to the plot.
There is an extensive website(d) dealing with all aspects of Tartessos, including the full text of Schulten’s book on the city. Although this site is in Spanish, it is worthwhile using your Google translator to read an English version.
(a) http://www.tolos.de/atlantis2E.html
(b) http://www.beepworld.de/members/atlantis_rainer_kuehne/
(d) http://www.tartessos.info/html/tartessos.htm

