Emperor Qin, also known as Qin Shi Huang, was the first emperor of a unified China. He ruled from 221 to 210 BCE and is best known for centralizing the state, standardizing weights and measures, and creating a uniform writing system. His reign marked the beginning of the Qin Dynasty, which laid the foundation for future Chinese empires. One of his most famous achievements is the construction of the Great Wall of China, which was built to protect against invasions. Additionally, he is known for the Terracotta Army, a collection of thousands of life-sized sculptures buried with him to accompany him in the afterlife.