Technically jc there is no actual proof that Yggdra killed anything besides a butt load of Bronquia guys, Nessiah, a prototype grim angel, a bunch of their servants and among other things, possibly a grim angel or two...
Also no, in the Ending D(the secret hard ending that you get if you beat #367) clearly states that the "Liberation Army"(I now do not consider them liberators now that they've successfully done the exact same thing that Gulcasa and his empire has done to Yggdra and the Kingdom, but getting back to what I was talking about, the ending clearly states that they fight the Seven Magi (and thus Hector) which was called "The Trial" and though I have to play Riviera again to see if they were any hints to said event happened...
Also to what you were implying, no you're thinking WAY before the events of...possibly before the first rulers of Paltina and Bronquia ever existed(and possibly even before Brongaa though he's probably thousands of years old himself) the great war between the gods and the demons actually...had demons in it, real demons not abnormally powerful humans that can destroy mankind with a bloody card, it's not possible and this isn't freaking Yu-Gi-Oh!
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