The first emperor of a unified China, known for his legal reforms and the Great Wall, was Qin Shi Huang. He ascended to the throne in 221 BC, unifying various warring states after the tumultuous Warring States Period. His reign saw significant achievements, including the standardization of weights, measures, and writing systems, and the construction of extensive infrastructure like the Great Wall of China. Though his autocratic rule faced criticism, Qin Shi Huang's contributions laid the groundwork for a centralized Chinese state that influenced future dynasties.