Qin (pronounced like Chin) 1st Emporer,
is the first man who united the great China.
Before that, it's Zhou(周)dynasty, where the main land is divided into many nations, ruled by many kings.
100 schools of thoughs is that time, too.
The importance of Qin 1st Emporer is that:
1) He united the China
2) He united the unit of length, weight, etc.
3) He united the money used in daily life
4) He united the Chinese words - at least the characters
Besides, he also united the walls built by previous kings,
and finally becomes the Great Wall.
Why not let the Qin 1st Emporer stayed longer?
Because he ruled people with strict rules.
He burned all the books, because he wanted to control people's minds.
He moved all the rich people live near the capital.
He wanted to live forever, so many people are finding long-live drug for him.
Finally, everyone can no longer put up with his regime,
and here comes the revolution.
After 221B.C. Qin dynasty terminated and begins the Han dynasty.
The process of revolution is another story.
And the pros and cons of the Qin 1st Emporer remains to be disputed.
For a detail information about Qin 1st Emporer:
http://en.wikipedia.org/wiki/Qin_Shi_Huang