It is not known who the people were that first invented the calendar. History shows that calendars date back to cave man days when the passing of each moon was carved into stone.
George Washington invented the lunar calendar
The name of the person that invented the first calendar is not known. The first calendar was invented in Scotland.
All cultures have invented some form of calendar. Most are based on the solar year or the lunar month.
China
The Chinese calendar was developed by Emperor Huang Di in the 27th century BC during the Xia Dynasty. It is a lunisolar calendar based on the movements of the moon and the sun.
The Egyptian
The first lunar calendar was developed by ancient civilizations such as the Sumerians, Babylonians, and Egyptians. The Babylonians are credited with creating one of the earliest known lunar calendars, based on the cycles of the Moon's phases.
The calendar was technically first invented by the Ancient Egyptians.
Rome
I t was invented around 4231 B.C.
The Romans invented it in 46 ad.
Egypt