Besides protecting china from foreign armies what other purposes could the great wall have served

To understand the Wall, we need to first understand why it was built. Most Great Wall histories tell us that it was built in order to keep out "nomadic tribes from the north". But who were they exactly?

Nearly half of Modern China is desert, mountain or arid plateau, particularly in the north. Throughout China’s history, the people from these unforgiving "northern steppe" areas lived in close proximity (often overlapping territories) with the Chinese. These northern nomads were certainly not all homogenous, however they shared many similarities and had distinctively different cultures and languages from the Chinese.

For over 2,000 years-they regularly harassed, invaded and even conquered the settled agricultural civilizations of the Chinese Empire.