The Han dynasty replaced the Qin dynasty in 206 BC and ruled China until AD 220 with only a brief interruption from AD 6 to 23.
Liu Bang was the first Han ruler. Then Empress Lu seized power from 195 to 180 BC and made her infant sons emperors. Wudi was the longest serving Han ruler. He reigned from 141 to 87 BC.
The Han dynasty extended China's territory into Vietnam and Korea. This was the most significant dynasty in China, comparable with the Pax Romana of Rome - a time of general peace. Education was highly valued and a class of scholars called "shi" was created. The Han dynasty is criticized for treating women as inferior to men. The Han dynasty developed the Silk Road, which allowed trade even as far away as the Roman Empire.
The dynasty declined in a similar way to the Roman Empire for some of the same reasons. After it fell, there was a time of disorder and China was ruled by regional governments called the Three Kingdoms.