sciencemag.org: Math whizzes of ancient Babylon figured out forerunner of calculus

Tracking and recording the motion of the sun, the moon, and the planets
as they paraded across the desert sky, ancient Babylonian astronomers
used simple arithmetic to predict the positions of celestial bodies.
Now, new evidence reveals that these astronomers, working several
centuries B.C.E., also employed sophisticated geometric methods that
foreshadow the development of calculus. Historians had thought such
techniques did not emerge until more than 1400 years later, in 14th
century Europe.

http://www.sciencemag.org/news/2016/01/math-whizzes-ancient-babylon-figured-out-forerunner-calculus