Qin Shihuang lived at the end of the Warring States Period. At that time, there were seven powerful vassal states in China, known as the "Seven Heroes of the Warring States" in history, and Qin was one of the "Seven Heroes of the Warring States" and the strongest.
"Sweeping Liuhe" means that Qin destroyed the six countries and the world belongs to it.
At the end of the Eastern Han Dynasty, Cao Cao wrote a poem called "Duguanshan", which expressed his concern for the people. That should be what it means.
In the Song Dynasty, Qin swept Liuhe, and Han crossed the mountain valley, which means unifying the world and caring for the people.