Your Facebook account should definitely not get blocked if you happen to clear your history. I clear my history every once in a while and my Facebook accounts do not get blocked. It must have something to do with your Facebook account itself (not clearing your browser history). It depends on multiple variables as to why your account was blocked.
It could be if you logged into your account using a bad proxy. It could be that you went against Facebook's TOS. Double check what you think you did then come back and add in detail of what things you might have done that could of caused Facebook to block your account.
