User blog comment:B214/General Discussion/@comment-9595671-20161227173051

We all know that the Dragons in DxD were once a more prominent faction than they've become in the present, but they're not a mythology/religion like the others. That got me thinking, regardless if the Great War or a lack of humanity's faith was the cause... what if there are some factions and pantheons that went extinct or completely disappeared?

While there's no physical evidence, the Old Satan Faction's actions were easily noted to be what would lead Devils to extinction... almost as if to say such a thing has happened once before. It could have been a mythology reflecting a religion now extinct or too small to still be one in the real world, or a species not tied to any myths as a whole like the Dragons.

To give one example, I know in real life Zoroastrianism is getting smaller and said may go extinct by the century, and their respective gods for good and evil would have given a great ally and adversary for each side to have. While one could say they didn't get put in the series because were too much like God and the Four Satans, it's possible they died out as Zoroastrianism faith kept dropping.

It's very likely that this will never be brought up in the story, but does it seem possible to anyone that there may have been one or more factions that were brought to extinction in some manner in the DxD world?