The Qin state was one of the seven major states during the Warring States period in ancient China. It was located in the northwest region and became known for its strong military and effective governance. The Qin state eventually unified China in 221 BCE under the leadership of Qin Shi Huang, the first emperor of China. The Qin dynasty, which followed the unification, is notable for its significant reforms, including the standardization of weights, measures, and even writing systems. The construction of the Great Wall of China and the famous Terracotta Army are also attributed to this period, showcasing the dynasty's ambition and organizational capabilities.