A lunar calendar is a calendar that is based on cycles of the lunar phases. This can be contrasted with the Gregorian calendar, which is a solar calendar based on the revolution of the Earth around the sun. Because there are slightly more than twelve lunations (synodic months) in a solar year, the period of 12 lunar months (354.367 days) is sometimes referred to as a lunar year.
The History behind it
The oldest known lunar calendar was found in Scotland at Warren Field and dates back to around 8,000 BC. Alexander Marshack, in a controversial reading, believed that marks on a bone baton (c. 25,000 BCE) represented a lunar calendar. Similarly, Michael Rappenglueck believes that marks on a 17,000-year-old cave painting in Lascaux represent a lunar calendar.