What are some examples of Buddhist rulers? I've been searching about this for a while, I have been looking for historical rulers who based their way of governing off Buddhist principles. But haven't been able to find a lot.
A good example is Asoka who ruled most of the India subcontinent  between 269 BCE to 232 BCE. He converted to Buddhism after witnessing the slaughter at Kalinga, a slaughter that he was responsible for. A rock inscription made at the time details this.


  His Majesty feels remorse on account of the conquest of Kalinga
  because, during the subjugation of a previously unconquered country,
  slaughter, death, and taking away captive of the people necessarily
  occur, whereat His Majesty feels profound sorrow and regret.


Asoka went on to rule for forty years on Buddhist principle and was one of the main people responsible for the initial spread of Buddhism out of the Indian mainland. He sent monks to many places throughout Asia and beyond including Mongolia, Burma, Afghanistan, Persia even as far as Turkey and Italy.

Such is his enormous repute they even made a Bollywood film about him. I have to confess that I've never seen it. I would be interested to know if it is worth the watch.

Additional Note

BBC radio have just done an excellent program on Asoka as part of the (also excellent) In Our Time series. Very much worth a listen if anyone is interested in this part of Buddhist history.