Hello,
You are allowed to roam the map freely, however certain areas may have certain consequences.
Without a doubt the safest area for you is your factions own territory, however PvP can mainly be found at the border territories of all the factions, PvP is still allowed elsewhere. Unclaimed territory can also be dangerous, as anyone could be there.
Going into another factions territory is allowed, but if they see you as a threat, they may retaliate. Of course if your faction is allies with the other faction, then there is no problem