Plimpton 322 is the Babylonian tablet containing a table of Pythagorean triples, centuries before Pythagoras.
Written in cuneiform on a clay tablet, Plimpton 322 dates to the Old Babylonian period, usually placed around 1800 BCE. It lists groups of numbers that satisfy the relationship later expressed by the Pythagorean theorem: the square of the longest side equals the sum of the squares of the other two sides.
The tablet is named after George Arthur Plimpton, whose collection at Columbia University held it. Researchers continue to debate exactly how Babylonian scribes generated and intended to use its numerical entries, but its sophisticated trigonometric or geometric character is clear.
Plimpton 322 is not a proof of the theorem in the modern Greek style, and it does not mention Pythagoras. Its importance lies in showing that Babylonian mathematicians worked with advanced numerical relationships roughly a millennium before Pythagoras traditionally lived.