The first "clock,” the gnomon, was invented in the 3rd millennium B.C. and has been attributed to both the Chinese and the Chaldeans. The gnomon was the precursor of the sundial, invented, according to some sources, by Anaximander of Miletus (Greece) in the 6th century B.C. and, according to others, by the Chinese and the Egyptians at a much earlier date.
The first artificial clock the water clock, or clepsydra, appeared at about the same time. The Egyptians in 3000 used the clepsydra alongside the sundial. (Inventions and Discoveries)