The overall strength of the Demon Realm is not much inferior to the Immortal Realm, but the Demon Clan Tribes are not united, which is why they are suppressed by the Immortal Realm.
Now that the Demon Race's Divine Son has been assassinated, it might become a trigger.
Youran True Sovereign said, "As far as I know, the Demon Realm's Demon Kings are divided into two factions: one advocating war and the other advocating peace. During the ancient wars, the Ancient Demon God was slain by our Human Race's Great Emperors, and the war-faction Demon Kings died, like the Ancient Thunder Dragon, or were injured, like the World-Ending Black Dragon, or sealed away, like the Candle Dragon. It can be said that the ancient war ended because the Ancient Celestial Court and the peace-faction Demon Kings made a vow, thus halting the war. The current Demon God still promotes peace. But if his only son was assassinated, and suspicion falls upon our Immortal Realm, I'm afraid war will break out again."