There have only ever been the most of 2 Sith at one time so how did they destroy thousands of Jedi?

In the ROTS novelisation Yoda says that the Sith have moved on from when they began, but the Jedi have not. The Jedi are incredibly arrogant and believe that their way is the right way, they seem too far stuck in the past.
But it seems the Sith understand that the galaxy has changed and has become more modern, people have tired over the old bureucratic ways of the Old Republic and are looking for something far more direct. Which brings on the Empire, who rules by the fist.
Anakin is a represntation in the SW galaxy of the changing times, he yearns for more action less talk and this is one of the things which draws him to the dark-side. If the Jedi were slightly more modern and had a better understanding the people that lived in their galaxy perhaps they could have beatin the dark-side, but in a galaxy where it is ruled by the fist the Jedi have no place.

Cheers!

MTFBY ALL!