If the words of the Grim Reaper were known to people of the world, an immense commotion would surely be caused. From his words, one could evidently infer that the western world was among the parties who participated in the world-destroying battle of Ancient Azure Mystic.
In addition, the vengeance of the Grim Reaper ran deep. He asked these buddhist cultivators why are they not in hell yet.
From this, one could tell that the Buddhist Sect was not a casual participant.