Si.427 is a Babylonian clay tablet that dates between 1900 to 1600 BCE. It was found in 1894 by a French archaeologist Scheil at Sippar, a site of an ancient Near Eastern Sumerian and later Babylonian city in the present day central Iraq.
The tablet depicts the applied mathematics used to accurately survey lands and measure their boundaries. This new discovery was made by Daniel F Mansfield of the School of Mathematics and Statistics at the University of New South Wales. It consists of three Pythagorean triples, making it the only known example of a cadastral document from the Old Babylonian period.