Talk:Grineer/@comment-167768-20150803063127/@comment-7645613-20150803072907

They raised against them due to the sentients popping up and probably using the grineer as pawns to help them destroy the orokin, although the sentients most likely were going to destroy them in the end if they won, but the tenno stopped the sentients before they could complete it. The lotus (or Natah at the time) may have did the same thing to the tenno, freeing them from their manipulation by the orokin and thus the tenno sought revenge against them as well, slaughtering them. Remember in rhino prime's codex, the orokin did cruel experiments on the tenno to make them what they are now, either through controlling them or by other means.

AS far as Tyl Regor knows, the sentients freed the grineer from the orokin from the kindness of their hearts.