Great Wall of China

The Great Wall of China is a vast system of walls, fortifications, and related defenses built across northern China over many centuries to guard and control the empire’s northern frontier.

Beacon tower: A tower used to send visual signals, often by smoke or fire, across long distances. Beacon towers relayed warnings along the wall faster than troops could travel.
Warring States period: The final centuries of the Eastern Zhou dynasty, when rival Chinese states fought for supremacy from 475 to 221 BCE. Several states built frontier walls before China was unified.
Ming dynasty military: The armed forces and defense system maintained by China’s Ming dynasty. Ming garrisons used wall fortifications to resist raids and organize frontier defense.
Nine Garrisons of the Ming dynasty: A set of major Ming military commands responsible for defending the northern frontier. These commands organized troops and fortifications along the wall’s defensive zone.
Great Wall of the Qin dynasty: The frontier defenses associated with Qin unification, assembled from earlier walls and later construction. Its history differs from the far better-preserved Ming sections commonly pictured today.
Watchtower: A fortified elevated structure used to observe surrounding territory and shelter guards. Watchtowers gave defenders sightlines over approaches and places to hold the line.
Qin dynasty: The Chinese dynasty founded by Qin Shi Huang that ruled from 221 to 206 BCE. Qin rulers linked and extended earlier northern defenses after unification.
Mongol invasions of China: The campaigns through which Mongol forces conquered territories across China in the thirteenth century. The wall’s defensive history is often framed by the threat of Mongol incursions.
Ming dynasty–Qing dynasty transition: The conquest and political upheaval that ended Ming rule and established Qing rule in China during the seventeenth century. In 1644, Qing forces entered China through Shanhai Pass after Ming defenses fractured.
Great Wall of the Han dynasty: The extensive frontier defenses built and maintained under the Han dynasty, including walls and beacon stations. Han defenses stretched westward and relied on materials unlike later stone-faced sections.

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