Eragon
A long time ago, the Dragon Riders kept peace in the world between the humans, dragons, elves, and dwarves. They were humans or elves bonded to dragons. However, the dragon of a human Rider named Galbatorix was killed by the Urgals (a species that fights a lot). Galbatorix became insane because of this. The Riders would not give him another dragon, so he decided to destroy them. He stole a black baby dragon and forced it to bond with him with evil magic. Then he and other traitors fought with the Riders. Finally, they killed them all and Galbatorix became king of the humans. The book Eragon begins 100 years after this. When it begins, Galbatorix is trying to find and destroy the elves (who are hiding in a forest called Du Weldenvarden), dwarves (who are hiding in the Beor Mountains - a gigantic mountain range reaching far above the clouds), and the Varden (a group of rebels hidden with the dwarves). He has not destroyed the elves yet, because he is still cautious of their power. He has not destroyed the Varden or dwarves because he cannot yet find them in the large mountain range.