The dynasty that ruled China during the construction of the Great Wall is the Qin Dynasty. Established in 221 BC under the leadership of Qin Shi Huang, the first emperor of China, this dynasty is credited with unifying the country and initiating several significant infrastructure projects, including the early construction of the Great Wall. The Great Wall was built to protect against invasions from northern tribes, particularly the Xiongnu. The Qin Dynasty's emphasis on centralization and defense laid the foundation for Chinese imperial history, and its influence is still felt in modern China.