At how many years of age do you have to get married in china?

In ancient China, girls got married between 12 and 14 years old and boys between 14 and 16 years old. Nowways, people in remote countryside also get married a bit early, 18-20 years old, others in towns and cities would get married after 23 years old. Some ambitious people would like to gain successful career first, so they choose to get married around 30 years old.