The Great Wall of China was built to protect the Chinese states and empires from invasions by nomadic tribes, particularly during the periods of the Northern Wei, Sui, and Tang dynasties. Construction of the wall began as early as the 7th century BC, with major sections built during the Ming dynasty (1368-1644). The wall served not only as a military defense but also as a means to control immigration and trade along the Silk Road. Its extensive architecture stretches thousands of miles and remains a symbol of China's historical strength and resourcefulness.