With no laws, all your left with is anarchy. The strong and rich will survive, the weak will perish or band together to survive. Its everything before the industrial revolution basically.
Monarchy and slavery = anarchy? ??
In large scale yes. No one had to really follow the rules, but if they didn't there were some people with force. You weren't forced to be a serf, but everyone had to eat... So alternatives weren't very good.