Mountains is a territory type available in every version of Deadlock. Mountains provide bonuses for Iron and Endurium production.

Population growth in this territory is slow, though not as slow as Swamps territories.

"Mountain territories have large amounts of iron. However, your population grows very slowly on this terrain. Ground units must go around the mountains on these territories' back edges before they can start fighting in these areas."

This means that the directions of possible attack are limited and you can place defenses to take advantage of this.