The first urban settlements on earth were in Mesopotamia, where man was able to prosper because of the geography – farming made easy. The technology of the Mesopotamians was not a secret for long, and it moved south to Egypt and westward over the Mediterranean.
The following chart shows this movement from Sumer to Greece over a 1500 year time span.
These are not movements of people in groups, they are the pathways of knowledge. Perhaps the craftsmen did move – the smiths and potters who were skilled enough to go with the highest bidder. Still, it was the absorbing of what was previously unknown that built the foundation of each successive society.
You see green arrows and white arrows, showing knowledge transfer by sea and by land. Funny thing about the land route, though. It stops at Troy. There is little evidence of knowledge crossing from Troy by land to the Greek Peninsula. Conversely, there is ample evidence for the sea route: to Crete, the Cyclades, and then Lerna in the Peloponnese.
Maybe this should be obvious, because man could transfer new ideas faster by sea than land. Trade would expose the importer to new wares and create demand for the style locally. Pottery styles follow the arrows as they make their way west. Still, individual differences remained. The Greeks never quite understood the Minoan pottery’s lack of precision. They admired the craft, and maybe copied the technique, but never gave up that which was uniquely Greek.