I think it would help if you would expand a bit on your question. The correctness of the assumption largely depends on why you assume that.

"Is it correct to assume that ancient Greece was tightly related to [earlier civilisations] because they all existed in the same general area?" Then the answer is "no", because that argument is not sufficient (there are plenty of examples of not-very related civilisations existing in the same area throughout history).

There might be other reasons to make that assumption though. I'm interested in hearing your arguments for why that assumption might be correct, and I'll be happy to discuss the merits of those arguments here with you.