Machinations of the Slave Lords!
Kara Tur, as originally presented in the Oriental Adventures supplement, does exist in our Greyhawk world (as the setting originally implied). The location of the continent on Oerth is as follows:
This map was found here
It was originally intended as an in-forum joke, but it works perfectly well for our purposes, and two characters—a PC and an NPC—have already hailed from there. Whether the PCs will ever journey to the realm is yet to be seen.