The Babylonians (1900-1600 BCE) were among the first civilizations to recognize π as a constant ratio, approximating it as 25/8 (about 3.125). They calculated the circumference of a circle as 3 times the diameter plus a small fraction. While Archimedes later refined the value, evidence shows Babylonian mathematicians understood the constant nature of this ratio centuries earlier. Ancient Egyptian mathematics also used a similar approximation.