I think you're misreading the text in that popup. The 'human sacrifice' is the amount of rice the farmers expect to be compensated with. There is sone evidence of actual human sacrifice in Burma, though- Moulmein palace was supposedly built after a human sacrifice.

It's important to note that "peaceful" Buddhism is a modern stereotype.

Also it has historically existed alongside folk religions and various other traditions e.g. Alongside Hinduism and Animist belief in Java where evidence of human sacrifice has also been discovered, or alongside Shintoism in Japan and Chinese folk religion in China. A more contemporary example of how Buddhism syncreticises is the way in which Western Buddhism is often practiced alongside New Age thought.