For three hundred years starting in 220 AD, China was divided into three smaller kingdoms (which were each still really pretty big). One kingdom was called Wei, and it was ruled by the Ts'ao family. It was in the northern part of China. Wei was not really strong enough to protect itself against invaders from the north, and soon some of these invaders, the Toba, took over ruling it.
The tomb of Liu Bei
The second kingdom was called Shu Han, and it was ruled by Liu Bei. It was in the south-west part of China.
The third kingdom was called Wu, and it was ruled by Sun Ch'uan. Wu was in the south-east part of China.
One of the great books of Chinese literature, the Romance of the Three Kingdoms, is about this time.
To find out more about this period 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!