Oh, it wasn't a war between Jedi and Sith. Our galaxy seems to have a fondness for erupting in galactic war every so many years. The most recent one was the Vong invasion. They're an extragalactic species that wiped out a good portion of the galaxy while trying to take over. Before that it was the Rebel Alliance vs. the Empire, and before that it was the Clone Wars with the Separatists. I think before that there was actually peace for a long time, unless I'm forgetting something else. I didn't really pay much attention in school.
There are holomovies about our galaxy, if you're interested. Books, too.