Suppose The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally built along an east-to-west line across the historical northern borders of China to protect the Chinese states and empires against the raids and invasions of various nomadic groups. The most famous and best-preserved section of the wall was built during the Ming Dynasty (1368–1644).
Can we infer that "The Great Wall of China was built to keep invaders out"?