In 581 AD, a general named Wen Ti from northwest China succeeded in conquering the other two kingdoms and establishing a new dynasty in China, with emperors who ruled all of China like the Ch'in and the Han. This was the Sui Dynasty. Wen Ti made himself popular by trying to make the government better than it was during the Three Kingdoms. Wen Ti ordered that poor people in the countryside should pay less taxes than they had before. And he sent men around to all the provinces to count how many people there were and how much land and money each of them had (this is called a census) so that the government would know how much taxes that province should pay. He ordered that every man should get a certain amount of land to farm. When the man turned 60 and was too old to farm, he would stop paying taxes and give back some of the land, and pass on the rest to his sons.
Wen Ti also decided to go back to the Han Dynasty way of picking his government officials through the university and the great examinations, to find out who were the smartest and best educated men (Women were not allowed to be government officials at this time).
Wen Ti died while he was still not old. He may have been killed by his son, Yang Ti, who wanted to be the emperor himself. In any case Yang Ti did become the next Sui emperor. Yang Ti wanted to be a great emperor, so he began a lot of important projects. Yang Ti's best project was one where people dug a Grand Canal which connected the Yellow River with the Huai and Yangtze Rivers and made it much easier to get from northern to southern China and back again.
But Yang Ti's worst project was that he attacked Korea to try to take it over. He got together a great army of over a million men to invade Korea, but his great army was defeated and had to run away. The army generals were angry about this and killed Yang Ti. That was the end of the Sui Dynasty.
To find out more about the Sui dynasty in China, check out these books from Amazon.com or from your library:
Eyewitness: Ancient China, by Arthur Cotterell, Alan Hills, and Geoff Brightling (2000). For kids, with lots of excellent pictures.
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 Sui Dynasty, by Arthur Wright (1978). Old, and not for kids, but a good discussion of the issues around Sui unification of China.