The story so far

Millenia ago in another world, a terrible being known as Saganthur won an ancient war against life itself in his quest to enslave and defile all of it. But the living would not give up so easily; the Mages of Uthurdan gathered together and poured their essences into a final project. This project was the enabling of an escape from Uthurdan, now only remembered as the Lost World, into the New World of Thule-Arpad. Since its creation, the world of Thule-Arpad was barren and only contained one being; the merciful and the mighty Arpad, a being with the power of creation. Upon the refugees entering his world, he embraced them immediately without question and changed his world so that it would be perfect for their habitation.(edited)

Natural features separated the Kingdoms of the various races, and Arpad himself anointed noble and wise Kings of old to rule and protect their realms. But peace was not to be. Saganthur discovered what the Mages had done and realized that those who resisted him had fled to another world, to be free of his tyranny. This was not acceptable to this monstrous being who sought to corrupt or destroy all that he could. He came to the world of Thule-Arpad and slowly corrupted from the shadow the order that Arpad had created. Fearful of the potential that Arpad had to destroy him due to his power and being a cowardly being, Saganthur did not reveal himself until all the cards were stacked in his favour.(edited)

The ancient lines that Arpad blessed were usurped, their former servants practicing witchcraft and summoning corrupt beings of darkness from Thule-Arpad, turning on their rightful and noble rulers. But Arpad was not helpless; the Kings and Knights of Old were equipped for this war and they struck a great many of the hellish creatures as well as denying the corruption of Saganthur.(edited)

But as the Armies of Thule-Arpad prepared for one final strike, an attack to close the Portal to the Lost World, they found themselves fighting endless hordes of corrupted beings who had once been their kin in a hellish, corrupted terrain which was unsuited to the very existence of life. The Armies of Arpad suffered many casualties and gained very little for it. In the end, to save the people of Thule-Arpad, Arpad threw himself at the hordes and slew a great number of them as well as banishing Saganthur into the Void. But the Lord of the Lost had anticipated this, and as he was struck from the world he took Arpad with him into oblivion.(edited)

So the portal remains to this day, and the corrupt thralls of Saganthur still seek to pour forth from the Lost World of Uthurdan into Thule-Arpad, only prevented by the noble efforts of what remains of Arpad's Knights of Old. It shall remain so until the people of Thule-Arpad honour the legacy of their Noble God and reclaim him from the Void.