One of the more significant Prime worlds, Oerth — the central world of Greyspace — has played a role in planar history for hundreds of thousands of years, dating back to the Battle of Pesh, the final battle of the War Between Law and Chaos fought upon its surface. In the modern era, it is one of the three strongest economic forces in Wildspace, and it has some of the greatest prevalence on the planes for a Prime world, third perhaps only to Ortho and Toril. Many arcane spells now common throughout the planes were first developed by some of Oerth's archmagi, and many of its powers have expanded their reach throughout the Prime and beyond (though according to some, they're merely seeking to expand their reach in advance of some foreseen downfall in the coming centuries). For those planars seeking to take in the Prime lifestyle, Oerth is perhaps the best choice for such, one of the most accessible and most representative worlds in the Material Plane.
Not often noted is the impact of Oerth on the Abyss and vice versa. Three significant abyssal lords — Fraz-Urb'luu, Graz'zt, and Zuggtmoy — each found themselves imprisoned on Oerth in recent years, each imprisonment significantly upsetting the balance of power on the Abyss and upending the plans of many. One of Lolth's greatest drow populations is found within Oerth's Underdark, as is her high priestess, and similarly the most significant non-gnoll followers of Yeenoghu, the Maure family, are of this world. The noted demonologist and conjurer Iggwilv, consort of Graz'zt, names Oerth as her homeworld, and their son, the cambion demigod Iuz, personally rules one of its nations. Altogether, events of the last two centuries have led near all powers of the Abyss to watch Oerth with a wary eye, knowing that whatever happens in the near future, this world is nearly certain to play a role.
- Fiendish Codex I: Hordes of the Abyss, pg.106
- On Hallowed Ground, pg.166
- Planewalker's Handbook, pg.33