to be honest once you've come up against the bosses once and learn them, you realise there are ways to tackle them even in early game gear. Remember the bow is your very best friend and that you can use it to kite enemies or even lure 1 at a time.

The mountains are tougher because the mobs are harder and also because you can get mobbed easily. The swamps are tough because you regen less because you are always damp. But once you figure out the tactics you'll be fine.