In the early 13 century, a Mongolian tribe from the north became very strong. Led by Genghis Khan, the Mongolians occupied Beijing, then the capital of the Jin. In 1260, Kubla Khan, the grandson of Genghis Khan established Yuan Dynasty. Kubla Khan set Beijing as the capital city. Unfortunately, the old city was destroyed during the war. So they had to rebuild it. 


In old China, all the structures and roads were required to be symmetrical. So the city was well designed. First, they had to find a centre, and then built a regular square city. After construction was completed, they asked all the residents who lived in the old city to move to the new one. 

In this newly-built city, you can find streets and Hutongs. At that time, there was a clear definition for a street or a lane. A 36-metre-wide road was called a big street (Da Jie). An 18-metre-wide one was called a small street (Xiao Jie). And a 9-metre-wide lane was called a Hutong.