The Battleground is the back-end area of the Volcanic Belt. Ferocious beasts such as Crimson Fatalis and Akantor usually live in this large space. It's used as a one-on-one fight between the hunter and a monster. Other quests such as Dual Kirin take place here. There is a base area, but it has no bed or supply boxes; also note it is impossible to go back to the base after leaving without dying or using a Farcaster.
There are a couple of gathering areas in the Battleground. They're small red bushes that you can gather Powerseeds and Armorseeds from.
This area also resembles Area 7 of the Old Volcano map.
There is a glitch in the area; when fighting an Akantor, if it digs towards you right at the start, you can jump up the ledge behind you, using the prolonged dive. This makes it easier to attack him with a Bow or Bowgun, but doesn't serve much purpose for Melee users. This glitch is completely harmless and has no effect on the PSP.
Also, the starting point resembles the Old Volcano secret area.
The lava here cannot be approached and so does not cause terrain damage.