Every Diablo game has a desert region, and Kehjistan is Diablo 4's. Players might remember some of Kehjistan's locations from Diablo 3: Alcarnus and Caldeum. The region's vast sands are littered with ancient ruins and artifacts[1]:
Perhaps the most important event known in Diablo 4 occurred in Kehjistan: the ritual that brought back Lilith, accomplished by cultists of the Triune faith. Also, lurking in the desert sands are demons of the Fallen monster family:
Blizzard also mentions that Kehjistan is inhabited by members of the Zakarum faith or "The Church of Light," as it's known in Diablo's lore. These followers are often so fanatical that they lose sight of good and become corrupted:
Xiphoid has been playing Diablo since the original's release in 1997. He made one of the largest Age of Empires sites in the late-'90s and early-'00s. Now, he runs MythicDrop.com, a premier Diablo 4 fansite.