663
Pythagorean Theorem Found On Clay Tablet 1,000 Years Older Than Pythagoras
(www.iflscience.com)
Subscribe to see new publications and popular science coverage of current research on your homepage
There are mentions of pythagorian triplets in pyramid era Egypt, and in all fairness, ancient Greeks didn't have symbolic algebra either - it is a fairly recent form of expression.
And, as far as I know, ancient Indians were actually writing mathematical expressions in full prose form - word problems et al.