 Ptolemy did not explain where this approximation came from and it may be assumed to have been well known by his time.It is unknown where in Mesopotamia YBC 7289 comes from, but its shape and writing style make it likely that it was created in southern Mesopotamia, sometime between 1800BC and 1600BC.Yale University acquired it in 1909 as a donation from the estate of J. P. Morgan, who had collected many Babylonian tablets; his bequest became the Yale Babylonian Collection.