Who were the first known people to use pi?

The first known people to use the concept of pi were the ancient Babylonians and Egyptians. The Babylonians approximated pi as 3.125 around 1900 BCE, while the Egyptians used a value of approximately 3.16 in their calculations, as evidenced in the Rhind Mathematical Papyrus. These early civilizations utilized pi in their geometry, particularly in relation to circles.