The dark age you describe is from 1100 to 800 BCE. Mycenaean culture precedes this. I think they use "Linear B" script. I do not know what stories and records we have from writings from this era. The timeline you present indicates about 600 BCE Solon visits Egypt. I think Solon belonged to a different Greek culture living in the same region, but the Egyptians would have identified him as being from that people group.
A question I have is - Did Solon and the Greeks living in that area understand this script or did they forget and adopt a new one? (from the Phonecians, I believe)
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I don't believe anybody linked the Wikipedia article. Here it is.
https://en.wikipedia.org/wiki/Atlantis
Timaeus is cited in the article:
Atlantic Ocean and the Pillars of Heracles
I do not know what names the Egyptians had for the Mediterranean Sea, the Western Mediterranean Sea, or the Atlantic Ocean. Is a misinterpretation possible?
I have the same question about the Pillars of Heracles. What did the Egyptians call it?
When I made the first post, I was going with a reference to the Sea Peoples invasion, but I thought they came from much closer than that, but what seems to be a very long way away. That would put the Atlantic Ocean and beyond the Pillars of Heracles an exaggeration. Maybe when Solon was visiting Egypt, he was having a discussion with their priests and comparing subjects such as Geography and History - and he was lining up the Egyptian story of the Sea People invasion with whatever story he had of a similar event.
The "navigable" part of the dialog might be an addition in order to leave open open questions out of the dialog.