There is debate whether the Pythagorean theorem was discovered once, or many times in many places, and the date of first discovery is uncertain, as is the date of the first proof. Historians of Mesopotamian mathematics have concluded that the Pythagorean rule was in widespread use during the Old Babylonian period (20th to 16th centuries BC), over a thousand years before Pythagoras was born.[68][69][70][71]
The German version also talks about the various roles Pythagoras might have had or not had regarding the theorem, and how research is unconclusive. One such possibility is that this older Clay Tablet applied the theorem without being able to prove it, and Pythagoras or one of his students could have found a proof.