I confused you for someone who'd take the new information and explore the details for himself. I'll be sure not to repeat such overestimation.
I'm certainly not here to provide any earth-shattering revelation about Pythagoras and the source of his theorem; this is no novel assertion on my part. That Pythagoras learned the relationship of a, b, & c in Egypt is a well-known bit of history. However, since you ask, here are a few references -
(1) http://www-groups.dcs.st-andrews.ac.uk/~history/HistTopics/Babylonian_Pythagoras.html --
"In this article we examine four Babylonian tablets which all have some connection with Pythagoras's theorem. Certainly the Babylonians were familiar with Pythagoras's theorem... All the tablets we wish to consider in detail come from roughly the same period, namely that of the Old Babylonian Empire which flourished in Mesopotamia between 1900 BC and 1600 BC."
(2) http://www.mathgym.com.au/history/pythagoras/pytheor.htm --
"Firstly, we need to appreciate that Pythagoras did not discover the relationship between the length of the sides of a right-angled triangle. This relationship had been known in Babylon and Egypt for centuries (if not millennia) before."
"One of the Babylonian tablets (Plimpton 322) which is dated from between 1900 and 1600 BC contains answers to a problem containing Pythagorean triples, i.e. numbers a, b, c with a² + b² = c²... It is said to be the oldest number theory document in existence. (Note Pythagoras lived from about 569 BC to about 475 BC)"
"In about 535 BC Pythagoras went to Egypt... In about 520 BC Pythagoras left Babylon and returned to Samos."
If you should require further assistance, don't hesitate to ask.