But there is no evidence of Proof before The Pythagoras. The documented evidence tells only the knowledge of the fact but no proof presented.Thanks for your feedback my dear friend @rycharde :))
There are differences in one Historian to another. I already wrote in the beginning that there is little or no proof of anything documented by The Pythagoras or The Pythagoreans. It's all based on later Greek Mathematicians or Philosophers' writings.
Yes, true, one of the tragedies was the destruction of the library of Alexandria, and one of the dilemmas is that Greek mathematicians often state they learnt their knowledge from Egypt yet, as you say, we have no logico-mathematical proofs from cultures before the hellenic.
Right, most of the great resources to justify the contributions of Thales and the following Greeks have been destroyed of lost!