How to remove plague By killing them all. That... if used modern day will be called as.......

Well he didn't kill them to get rid of plague. It was out of pure rage for his brother.

actually if we think about it he did eventually found a way to get rid of the plague :| ... and brought back his brother from the land of the dead, so I have a question? if he was able to bring back his brother why did he make a fuss and killed all the villagers? :/

(●￣(ｴ)￣●)

AND he did bury them all, so much work just to avenge your brother who will come back to life #－.－)

The ritual is a taboo and pretty sure it wasn't his plan to revive his brother but just found himself needing so. He wasn't thinking when he went berserk to kill all those people. It was an impulsive reaction from pain, anger and sadness. He's naturally a good guy, after all he worked his ass off making a cure for the plague, so he ended up burying the corpses.

I thought he had to kill people to succeed with the ritual (Fullmetal alchemist thingy) but I guess not...

I dont think he killed them with the ritual in mind, I feel like he was in rage with the fact that the villagers created rumors about having a twin is bad and the need the kill one of them leading to the suicide of his brother

Yup. Well the story never mentioned that it was a requirement in the ritual to kill an entire village. But then how will the ritual be taboo without anything in exchange? My theory is that Taoist brother was able to perform the ritual due to the lives he took. After his unprecedented genocide, he realized what he's done, felt the guilt, missed his brother, thought to bring him back and made use of the blunder genocide to create a kyonshii. The massacre was never planned but found he can use it to revive his brother.

Yep your on the point