The Great Wall of China was primarily built during the Ming dynasty, which lasted from 1368 to 1644. Although some portions of the wall were constructed earlier by various Chinese states and dynasties, the Ming dynasty saw significant expansion and reinforcement of the structure. The wall served as a defensive barrier against invasions from northern tribes, particularly the Mongols. The Ming emperors commissioned thousands of workers, including soldiers, peasants, and prisoners, to create and maintain the wall. It stretches across northern China, showcasing remarkable architectural ingenuity and is a UNESCO World Heritage site, attracting millions of visitors annually.