To understand the Kedethian Decree, we must first understand the Kedethian Ascendency, a philosophy as ancient, rich, and powerful as the Kingdom of Kedeth itself.
Kedeth is one of the two oldest and most established kingdoms in Arelatha--the other being Lothania--and at various times has occupied or controlled the entire western half of the continent, from the Dragoncrests to lands north and south of The Deepening. From the inception of the first Kedethian dynasty over 3,000 years ago, Kedethians have believed that they are the rightful inheritors of the land and the natural rulers of it. Pride in Kedethian lineage sometimes fuels an overt racial and/or national prejudice, but this pride also helps preserve their rich heritage through annals, fastidious traditions, centuries-old days of remembrance.
The Kedethian Ascendency is both a geographical area and a belief system. In terms of geography, it refers to all lands governed by or owing fealty to the Kingdom of Kedeth. This currently includes Elandra, Alikon, Ogria, and by implication the Greenbrier Forest (Vashan) and the free cities of Cer Vedrys, Cer Cannaid and Cer Halcyon. In terms of belief, it refers to the expectation that all lands will eventually bow before the Kedethian crown. Various Kedethian sages, seers, and prophets have proclaimed it to be so in a body of written works known as the Kedethian Decree, which date back over 2,500 years.
These oracles have been interpreted in a variety of ways by different peoples. The outlying duchies and fiefdoms of Elandra and Alikon generally exercise a "wait and see" approach while focusing on living peacefully with their neighbors. The free cities, as conglomerates of all types of people, are largely content to be melting pots of styles and conflicting philosophies, preferring variety over homogeny. Ogria has largely abandoned the philosophy altogether. This means the Kedethian Decree is largely isolated to the Kingdom of Kedeth.
That doesn't mean Kedethians have held to the tenets of the Decree consistently, either. Throughout history, various ruling dynasties that have wielded the scepter on the throne at Oljin have disagreed about how best to enact the Decree. The Chronicles of Kedeth record heights of national pride, featuring frequent conquests and land acquisitions, as well as relative laxity accompanied by royal grants of freedom and autonomy to previously conquered territory. Because the Decree can be--indeed, has been--interpreted so broadly, the Kingdom of Kedeth has not made any significant inroads into having "all lands bow before the Kedethian crown."
One fanatical interpretation of the Decree has surfaced in recent years: a purely racially motivated and particularly brutal take on the philosophy adapted by the Nephreqin. Taking the idea of "ascendency" and "continental rule" to its extreme, this offshoot of pure Kedethian bloodlines has determined that all non-Kedethian people are a "lesser" form of human. Not only that, they also believe any Kedethians who disagree with their views are to be subjugated for abandoning the Decree. To the Nephreqin, the Decree is the supreme "law," though it is no actual law. And under this "law," they have decided to execute judgment upon the peoples of Arelatha, forcibly ushering in the Ascendency by any means necessary. Which is not a Kedethian quality at all.