After the Zhou dynasty lost their power ancient China was a land of warring states. Which state gained the most power and united China?

The Qin state

Explanation:

Warring States Period is a period in the history of China that existed in 475 - 221 BCE. History shows that it was time when China had many rival states that fought for territory and dominance. The Qin state was one of the state that became powerful and victorious in the end and established the first unified Chinese state.

Zhou (Chou) Dynasty existed between 1046-256 BCE. The leaders are said to ruled alongside the Shang dynasty, after which they took over. History shows that it was stable for 200 years, but it did started to collapse with increasing local interests of more than 20 feudal lords, creating the Warring States Period.

The 7 major states of the Warring States Period are Han, Wei, Qin, Zhou, Chu, Qi, and Yan..