There are a number of lunar calendars that have had long use. The Jewish, Islamic, and Chinese calendars, for example. They are a bit complicated for that reaso

There are a number of lunar calendars that have had long use. The Jewish, Islamic, and Chinese calendars, for example. They are a bit complicated for that reason. The Jewish calendar has the equivalent of "leap months", for example, while the Islamic calendar has a "year" that is ~10 days shorter than an astronomical year.