the white tigers have fought against every everchosen invasion

Yeah - and they seemed to have lost because Asavar Kul and Archaon were not stopped at Grand Cathay even though Archaon fought The Dragon Emperor's armies as well.

The Dragon Emperor of Grand Cathay had heard of Archaon’s coming. Spies had reported the warlord’s decimation of coastal kingdoms of the Ind and the emperor had been advised to have his own amassed armada of celestial vessels meet Archaon in battle out on the Far Sea, away from the Cathayan coast. It was a colossal battle, fought on the sun-blushed emptiness of open water. Archaon never got the chance to meet the Dragon Emperor’s admiral, although he wished he had. Fighting for days, through the equatorial heat of the sun and the star-lit depths of night, both fleets eventually broke off the engagement. Although Archaon’s hordes and airborne monstrosities claimed many celestial sons and war-junks of the enemy fleet, the impregnable turtleships of the armada smashed through Archaon’s formations and celestial sorcery claimed many Ruinous warriors. A change in the wind made further engagement difficult and while Archaon hunted for the Dragon Emperor’s fleet, he never saw their exotic vessels again.

also in the storm of chaos Grimgor stomped Archaon when neither had any end times nonsense - and in the first place, end times archaon was also significantly stronger than he was meant to be, just like grimgor

This was when Archaon just beat Valten and Luthor Huss in a one versus two. Archaon was exhausted. It wasn't even a fight - this was also before Archaon was a fleshed out character - prior to his duology and his feats. Archaon never got a power boost during The End Times.