An Indian text written the same year that Rome fell—476 AD—shows the influence of Greek, Egyptian, and Babylonian mathematics, brought by Alexander as he penetrated Indian lands. Like the Egyptians, the Indians had rope stretchers to survey fields and lay out temples. They also had a sophisticated system of astronomy; like the Greeks, they tried to calculate the distance to the sun. That requires trigonometry; the Indian version was probably derived from the system that the Greeks had developed.
