Question

What is a lunar calendar and who created it?

Answer 1

A Lunar calendar is based upon the Moon cycle of Moon phases. The Sumerians.

Answer 2

The lunar calendar became the basis of the calendars of the ancient Chinese, Babylonians, Greeks, and Jews

Greek astronomers also devised rules for intercalations to coordinate the lunar and solar years. It is likely that the Roman republican calendar was based on the lunar calendar of the Greeks