The Incan Empire was located on the western side of South America. Although the Empire was huge, it can be easily divided into three geographical regions - mountains, jungle, and desert.

Andes Mountains: North to south were the Andes Mountains - home of the Inca civilization. The mountains dominated Incan society. The mountain peaks were worshiped as gods. 

The Andes created a natural barrier between the coastal desert on one side and the jungle on the other. The snow-capped mountains were full of deep gorges. 

The Inca built bridges across the gorges so they could reach all parts of their empire quickly and easily. These mountain gorges were natural barriers. If an enemy approached, the Incas could simply burn the bridges.

Amazon Jungle: On one side of the Andes was the Amazon jungle. The Incas must have entered the jungle occasionally, as they did know about the many valuable things that could be found in the Amazon, like wood and fruit and natural medicines. But they never established settlements there. They had no desire to live in the jungle. The Incas expanded north and south instead.

Coastal Desert: Between the mountains and the Pacific Ocean is a coastal desert 2000 miles long and between 30-100 miles wide. The desert provided a wonderful natural barrier. Some scientists think it is the driest place in the world. It is not completely barren. There are fertile strips where small rivers and streams run from the Andes mountaintops to the sea.