The Barren Mountains is a battlefield out the mountains west of BattleTerra's Dojo. It is rough, rock, and hard to breathe. It is only available to the finest warriors.
After a retired battle-penguin was found almost dead near the Dojo mountains due to an avalanche, scientists found the Avalanche did not come near the Dojo, but instead came from elsewhere. Explorers did search when they found the spot. Further north they went. They got to the top and the mountain and stuck a flag in it. They could not breathe, and fell due to the lack of high amounts of air. The battle penguins followed the footprints, and trained there. Due high performance requirements allows them to be in top shape.