In this scene we can identify that Genghis Khan was then considered the supreme ruler of the Mongol empire and lead his military to conquer many countries and become one of the biggest empires.
In this scene it is showcasing the Mongol army conquering China, after having rule over all of china they had no idea on how to rule or take advantage of China for their benefit and in the end, they ended up leaving China afterwards.
After taking over China, they also moved on to Persia and conquered their entire empire in Iran. Persia still had control over their government however many Mongols turned over to Persian society. As seen in this scene some people didn't surrender and would be killed on the spot.