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. It was originally built to protect the Chinese states and empires against invasions and raids. The total length of all the walls built over different periods measures over 13,000 miles.
Can we infer that "The Great Wall of China was built in a single period."? Yes, no, or maybe?