Use the oasis to hunt for materials to craft into items and to trade in the local tribal camps.

Beware of monsters within the oasis, they will appear at random to fight you, though you can run from them.

The better equipment will be in the dungeons, however they may not provide 'effects' and such, so sometimes the lesser equipment may be best.

If you save the bison the storyline will become extended. Won't spoil, but this is the only way to get any of the intimate scenes in game.

There are three 'shrines' that seal powerful monsters and a optional boss, beware them if you are alone. 

There is a special cavern with an optional SUPERBOSS more powerful than the final battle. Take care if you find this place.

You can sleep in bed and randomly get an intimate bathing scene, its random to get it, but you will know it once you do.