Han Dynasty China
Kao Tsu (Liu Pang), when he established the Han Dynasty in 202 BC, didn't really change that much from the system that Ch'in had set up. He still got the kings and their families to live at his capital city, and he still sent out governors and judges whom he could trust. But Kao Tsu didn't kill or exile the scholars anymore. Instead, Kao Tsu called for smart educated men to work for him, to be the governors and judges he needed, because he knew they would be good workers and make fair, wise, decisions (but still he would not let any women be judges, no matter how smart they were).
Kao Tsu did allow some areas to have their own rulers, if the rulers were really loyal to him. This earlier part of the Han Dynasty is called the Western Han, because Kao Tsu's capital was in Western China, at Chang'an.
Kao Tsu's wife was the Empress Lu. When Kao Tsu died, Lu tried to take over power for herself, and she succeeded in controlling Chinese politics for some time, even though it was very difficult for women to get political power at this time.
In 141 BC, Wu Ti became emperor. Wu Ti was called the Martial Emperor, because he led many campaigns against the Huns (the Chinese called the Huns the Hsiung-Nu). At this time, the Huns were living north and west of China, and they tried to invade all the time. Wu was able to set up a safe and peaceful trade route called the Silk Road for sending Chinese silk and other things across Central Asia to West Asia, Egypt, and the Roman Empire, in exchange for Roman gold.
Wu Ti also set up the first university in China, in 124 BC. Young men (only men were allowed to go to university then) were chosen for being very smart and hard-working and then the government paid all their expenses while they went to the school. At first the university had only fifty students, but it grew quickly. Students at the school mainly studied Confucian philosophy, which Wu also made the official state philosophy. Now men who wanted to become governors and judges had to pass a very difficult examination to see if they were smart and well educated enough.
In 111 BC, Wu Ti invaded northern Vietnam, and made it part of the Han empire. And in 108 BC, he invaded northern Korea and took it over.
Wu Ti died in 87 BC.
Bibliography and further reading about the Han dynasty:
Eyewitness: Ancient China, by Arthur Cotterell, Alan Hills, and Geoff Brightling (2000). For kids.
China (History of Nations), by Greenhaven Press (2002). For middle schoolers. The negative review on Amazon is actually for a different book - don't be alarmed!
The Cambridge History of China: Volume 1, The Ch'in and Han Empires, 221 BC-AD 220, edited by Denis Twitchett, Michael Loewe, and John K. Fairbank (1986).