Okay kiddo, so a long, long time ago there was a man named Qin who lived in China. He wanted to be in charge of all of China and make it all one big country. But, there were lots of other people who also wanted to rule over different parts of China.
So, Qin started to fight with these other people and attack their armies to try and make them agree to be part of his big country plan. It wasn't easy, but Qin was a really good leader and strategist, so he was able to win many battles.
During this time, Qin also came up with some new ideas for his army. He created new weapons and organized his soldiers in a way that made them very strong and hard to beat in battle. He also made sure everyone was very disciplined and followed his orders without question.
Finally, after many years of fighting, Qin was able to conquer all of the other groups and kingdoms in China and make them part of his big country. This was called the "unification" of China.
To celebrate, Qin became the first emperor of China and started a new dynasty, called the Qin Dynasty. He also began many new projects, like building giant walls and palaces, and created new laws to help govern his people.
And that, my little friend, is how Qin's wars of unification helped create one of the most powerful countries in the world - China!