Kublai Khan moved the capital from Karakorum in Mongolia to Khanbaliq located in Northern China. In modern times it is now called Beijing.
The Mongols conquered Southern China and ended the Song dynasty. Yuan means "beginning," it means the Mongols planned to rule China for a long time. They gained control of the Silk Road. This brought them wealth through trade. They became very successful.
They were tolerant of other religions. More people liked their ways and didn't feel the need to rebel. More people got the Scholar-Officials job. Their government was improved with more people working behind desks. The Mongols ruled at the top and did not mingle with the Chinese. These ways held peace and prosperity for a long time.
Marco Polo was a famous European traveler. He fascinated Kublai Khan. He was given a special status from Kublai Khan for 16 years. He ruled the Chinese city Yangchow. He was sent in business-trips during this time. He wrote a book and tons of Europeans were amazed by his adventures in China.
The Mongols had very successful trade. They took over the Silk Road. They taxed people on the Silk Road. They grew wealthy through these taxes and on top of that they were trading with people on the Silk Road. There trade spread far and eventually they started to trade by sea and not just by land. The economy was boosted because people were selling more things.