Greek Colonisation is something of misnomer on two counts. First of all is the fact that there was no unified Greek state until the time of Alexander the Great. Instead the territory was fragmented into a number of competing city- states (poleis) that formed shifting alliances to meet the exigencies of the day.
Secondly, the term ‘colonisation’ did not mean the same then as it does today. Individual city states had their own expansion ambitions, which were generally concerned with trade rather than territory. It seems that most of the colonies began as trading posts, known as emporia(a) , some developing into towns, others grew into urban centres and even established colonies of their own.
In the first millennium BC, some of the Greek city-states gradually expanded their influence(c) eastward into Asia Minor and the Black Sea and westward along the northern coast of the Mediterranean, eventually founding Massalia (modern Marseilles), which established emporia in eastern Spain.
The Phoenicians had their own city-states such a Tyre, Sidon and Byblos. They established ‘colonies along north Africa, and Spain. They competed with the Greeks, particularly in the central Mediterranean, where at one point they shared Sicily. Settlers from Tyre founded Carthage, which in turn became more powerful than and independent of its parent city and became more belligerent, eventually engaging in a series of wars with Rome, which it lost.
There is much more relevant information to be found on the excellent Ancient History Encyclopedia website(b) .
The River Danube is the second longest river in Europe, which was known to the ancient Greeks as ‘Istros’. It rises in Germany’s Black Forest and after passing through many countries, including four capital cities, it eventually empties into the Black Sea.
A number of researchers have associated the river with Plato’s Atlantis. One of the earliest was Nicolae Densusianu who proposed that Atlantis had been situated in ancient Dacia, his native Romania. Over a century later some of his ideas have been revived by other Romanian commentators such as Adrian Bucurescu and Alexandra Furdui. Densusian’s nationalism is now frowned upon and there is an understandable suspicion that his modern Romanian supporters may have similar underlying motivations.
There is a gorge on the Danube known as the Iron Gates which provides part of the boundary between Serbia and Romania. Densusianu located the Pillars of Heracles at the Iron Gates, an idea supported by Ticleanu, Constantin & Nicolescu who place Atlantis further west on the Pannonian Plain. However, Ranko Jakovlievic expressed the view that the Iron Gates section of the Danube was the location of Atlantis!
Christian and Siegfried Schoppe locate Atlantis east of the Danube Delta on Snake Island in the Black Sea an idea now adopted by George K. Weller (a).
Alexandra Ioana Furdui, is Romanian by birth, an architect by profession, who now lives in Australia. Her interest in ancient history has resulted in a book entitled Island: Myth…Reality …or Both?  in which she posits Atlantis as a large island in the antediluvian freshwater Black Sea ruled by the Titans of Greek mythology, some of whom later started another civilisation in the lower Danube, where she claims the Pillars of Herakles were situated, which is probably the result of being influenced by the earlier work of Nicolae Densusianu.
Petko & Dimitar Dimitrov are a Bulgarian father and son team, who have written about the pre-flood Varna civilisation which they claim existed on the then exposed Black Sea plain, however, they do not call it Atlantis by name. Their book is available, in English, online(a) as a pdf file.
Their book, The Black Sea, the Flood and the Ancient Myths, which supported much of Ryan & Pitman’s work. Unlike them, who based many of their conclusions on a study of molluscs, the Dimitrovs focused on sedimentation evidence. They also suggest that the Holocene influx into the Black Sea also triggered the Vedic Aryan migration to India(b).
The Caspian Sea is not usually associated with the story of Atlantis, but as early as the 19th century Moreau de Jonnès proposed the Sea of Azov as the location of Atlantis and that the Black, Caspian and Aral Seas were just remnants of a large ocean.
While this may sound like a wild idea, one modern researcher, Ronnie Gallagher, has written an important paper(b) supporting the concept (see fig.8). This enlarged inland sea is also thought to have extended as far north as the Arctic.
Fessenden cites Strabo (Book 11:7;43), who recounts a tradition that the Caspian had been connected with the Black Sea by way of the Sea of Azov.
Modern proponents of Atlantis in the Sea of Azov have suggested(a) that at the end of the last Ice Age floods of meltwater poured into the Caspian Sea, which in turn escaped through the Manych-Kerch Gateway(c) into what is now the Sea of Azov, but at that time contained the Plain of Atlantis!
Immediately to the south of the Caspian are the Caucasus Mountains which have also had links with Atlantis proposed.
Adrian Bucurescu is a Romanian ethnographer and a prolific article writer and also the author of Dacia Secreta and Dacia Magica. He identifies the Black Sea and what is now mainland Romania as the home of Atlantis. He locates the Pillars of Hercules at the Danube gorge at the mouth of S-W Romanian river Cerna (also known as Acheron, Charon, Geryon) and that the capital of Atlantis was the city of Tulcea (Tul=atlas+Cea=land) at the Danube Delta.
Furthermore, Bucurescu claims that Plato originally said 5,000 not 9,000 years had elapsed between the Atlantean war and Solon’s visit to Egypt. He bases this idea on his claim that the works of the Greek philosophers were preserved in Arabic translations after the fall of Constantinople and that their numbers ‘5’ and ‘9’ were sufficiently similar to have led to a transcription error!(b)
However, a further contribution on Graham Hancock’s website has him listing the ten kingdoms (of Atlantis) extending over a much larger region, including Poland, Egypt and Sumeria(a)!
William Ryan & Walter Pitman published evidence, in 1997, that extensive flooding of the Black Sea occurred through the Bosphorus around 5600 BC. Controversy still surrounds various aspects of their
theory, some even claiming that the Black Sea broke into the Aegean, an idea that may be partially true(d).
Nevertheless, their conclusions were challenged in a paper(c) by Yanko, Gilbert and Dolukhanov, who offered evidence that the flooding of the Black Sea was not the rapid event claimed, but was spread over millennia, initially in the form of freshwater from the Caspian Sea via the Manych Spillway(d) as the glaciers retreated and later with seawater from the Mediterranean. The same paper concludes with the following; “The public perception that ‘Noah’s Flood’ happened there is not supported by any scientific evidence.”
Ryan & Pitman later published their theories in book form as Noah’s Flood and was understandably seized upon by many as proof of the veracity of the Bible. In fact a year before Ryan & Pitman launched their book, René & Denise Capart published l homme et les déluges, in which they linked the Black Sea with the the Deluge of Noah. A Bulgarian father and son team, Petko & Dimitar Dimitrov, refer to the pre-flood Varna civilisation existing on the Black Sea plain, but not calling it Atlantis by name. Their book is available online(a).
Inevitably, I suppose, Atlantis has been more firmly linked with this event by a number of commentators, particularly, Christian & Siegfried Schoppe(b). However, Hristo Smolenov also claimed that swathes of the Varna civilisation were inundated by the rising waters of the Black Sea but had no hesitation identifying it with Atlantis.
André Capart (1914-1991) was a former head of the Belgian Royal Institute of Natural Sciences and has also directed oceanographic research for NATO. Professor Capart and his anthropologist wife Denise (1918-2011) believed that the Atlanteans originally came from Libya and invaded the Aegean setting up their colonial capital on Thera(a). Capart and his wife were planning an expedition to Santorini in the late 1980’s, but it appears that no report of their findings has been published.
In 1986 the Caparts published L’ homme et les déluges which deals with the recurring cycles of ice ages, changing sea levels and the associated floods. They linked Noah’s Flood with the Black Sea(b) over a decade before Ryan & Pitman published their better known book, Noah’s Flood.?
Jon Nelo Juganaru (1948- ) is Romanian by birth, but emigrated to the United Staes, where he laboured as a glass artist and now writes under the pen-name of ‘Raven Alb J.’
His 2012 book, Why and How the Ice Age Ended, is a large tome that should have been edited to fraction of its size. As the title suggests it deals with the ending of the of the last Ice Age, which he claims was caused by an asteroid impact that also led to a Pole Shift. Another consequence was the destuction of Atlantis, which Juganaru identifies as Europe with its capital city situated in the Black Sea.
Among a number of his odd claims is that Göbekli Tepe is a miniature of Atlantis!
Throughout the book the author constantly introduces Romanian words for explanation, to the point where it quickly becomes irritating. Furthermore, he is also guilty of what for me is the publishing crime de la crime relating to non-fiction books, there is no index.
Bulgaria has not been totally excluded from the search for Atlantis. In 2012 it was announced that the oldest European town had been discovered in Bulgaria(a), near the town of Provadia and dated to about 4500 BC. Recently there were metal beads discovered in Bulgaria tentatively dated to 6000 BC. Along with recent discoveries of hoards of Thracian gold it is obvious that Bulgaria was no backwater, although identifying it with Atlantis is not a runner.*[Nevertheless, some have attempted(e) to link Atlantis with the ancient region of Thrace, which today would occupy a section of Bulgaria along with parts of Greece and Turkey.]*
In the mid-20th century the noted Bulgarian astronomer Nikola Bonev placed Atlantis in the Atlantic. However, the flooding of the Black Sea as revealed by Ryan & Pitman triggered the imagination of a number of people. The Schoppe father and son team who favour a Black Sea location for Atlantis have broken with the generally held view that Gadeiros, the twin brother of Atlas, gave his name to the city of Gades, now Cadiz in southwest Spain and proposed the more radical view that he gave his name to the Getae who occupied parts of today’s Bulgaria and Romania(b).
In 2012, Hristo Smolenov went further and suggested a closer connection between Bulgaria and Atlantis on his website(c), a video(c) and a book, Zagora – Varna: The Hidden Superculture.