In China, as in West Asia, India, or Africa, most people have spent most of their time farming for the last ten thousand years. In northern China, people mostly farm wheat, while in southern China it is mostly rice.
A video of people picking rice:
But when the great empires formed, about 500 BC, people in China also began to trade a lot with other people all across Asia, along the Silk Road. Some of the traders went south to India, and some went along the northern Silk Road through Uzbekistan to the Persian Empire. China shipped silk, tea, and porcelain west to Central Asia, and imported horses, gold, silver, wool carpets, glass, and steel.
People first used cowrie shells for money in China as early as 1800 BC, under the Shang Dynasty. People used cowrie shells for money all across Asia, and in Africa too. Cowrie shells were rare enough to be valuable, and small enough to carry conveniently. But later, when it was hard to get enough cowrie shells, people in China switched to using metal imitations of cowrie shells, and then metal strings of beads called cash.
We don’t know whether the idea to make coins with writing on them guaranteed by the government came from West Asia or not. But there were definitely bronze coins in China by the 400s BC in the Zhou Dynasty.
Another important industry in China was mining. In the Han Dynasty, people in China began running businesses digging deep pits to get salt to sell. Most of the men who worked in the mines were probably slaves. Around the same time, Chinese silk workers developed steel sewing needles so they could sell fancy embroidered silk cloth. Then Chinese traders began to sell a new Chinese invention, paper, on the Silk Road too.
As the Silk Road continued to bring imports to China, gradually people in China began to make some of these things for themselves. By the 400s AD, Chinese manufacturers were blowing their own glass. About 1200 AD, with the encouragement of Kublai Khan, they were growing their own cotton, and spinning thread much faster on the new spinning wheels.
Bibliography and further reading about the ancient Chinese economy: