Level 40-48 (Mohenjodaro Graveyard):

Mohenjodaro is a very annoying place but its also the location of some of the easiest enemies if you know how to fight them. The Harpy in the first part are annoying because they fly and have Mana Burn and Self Destruct. They are not worth training on for anything. The Rakshasa mobs on the second part are a good place to train. They have a powerful attack, but low HP. The blue ones are weak against skills and strong against normal attacks. The rest are just weak against everything. The third floor is also easy to train as well. The red Yama mobs heal the other ones and only the blue and red with gold ones attack. They are also very weak so its possible to kill them fast. If you reach level 44, you can attempt the Beast Trainer quest and enter the Shadow Dungeon. Do not even try the Shadow Dungeon alone you need a party to survive. Enemies on the second and third sections of the dungeon drop Giant Crystals which you may need for your Beast Trainer or Exorcist. The Ravana mobs on the second section of the Shadow Dungeon are a nice place to farm until you are level 48.

Level 48-54 (Bran Castle):

The bats are annoying and aren't worth training at. Starting at Bran Castle there are more than one quest chain. You will also get a huge increase in gold reward per fight as well. One is the main story quest, and the other is a side story that parallels the main quest so you can do both at once. The side story offers good rewards on the side in addition to money and experience. The side story gives you 300 Iron Doll summons for your Beast Trainer. Quests at this point also start providing stamina per quest. Starting from Bran Castle, you will also encounter mini boss mobs on occasion that have a high drop rate for boxes but have a large amount of HP and a decent attack power. They also tend to be about 10 levels higher than the recommended level of the dungeon. The first good training spot is at the Hell Hounds and Cerberus near the entrance to the second floor. The mobs here have low damage and low HP. The second spot is in the Bran Castle Jail. The Iron Doll Magicians and Iron Doll Warriors have low damage and good drops. The Magicians are weak against physical while the Warriors are weak against skills. Take out the Magicians first because they can use Beast Summon. The Shadow Jail is a fairly good place to train too. If you have a group of 3 the final section before the boss is good. Alloy Dolls follow the same set up as the Iron Dolls. If you're in a group of 2 the second floor is the best because those guys are weak but the drop rate is noticeably lower. If you did not need to grind before, chances are this will be the first time you need to grind before you can fight the boss or go to the next dungeon.