Suppose The Great Wall of China is the collective name of a series of fortification systems generally built across the historical northern borders of China to protect and consolidate territories of Chinese states and empires. It was constructed to protect against invasions and raids by nomadic groups from the Eurasian Steppe. The wall stretches from Shanhaiguan in the east, to Lop Lake in the west, along an arc that roughly delineates the southern edge of Inner Mongolia.
Can we infer that "The Great Wall of China was built in a single phase."? Yes, no, or maybe?