Is there a particular area or time you're interested in? How are you defining "early days of civilization?" Keeping track of astronomical cycles and coordinating celebrations with them is a longstanding tradition, but the exact practices will vary based on when and where you're talking about.

Sorry, we don't allow throughout history questions. These tend to produce threads which are collections of trivia, not the in-depth discussions about a particular topic we're looking for. If you have a specific question about a historical event or period or person, please feel free to re-compose your question and submit it again. Alternatively, questions of this type can be directed to more appropriate subreddits, such as /r/history or /r/askhistory.

Please try to be a little more specific in your question :)