These rules can originate from any number of sources: they can be religious rules, social rules, cultural rules, ethical rules, moral rules, etc... Some are written down but not always in official legal texts, some are passed down orally - but all of them, when broken, have consequences. So it's very, very broad.
In any system, be it big or small, there needs to be some kind of overarching framework of governance in every system - whether these governance structures are formal or informal