On the eastern edge of the Twin Seas lie the emerald jungles of Kehjistan. Several thousand years ago, hunter-gatherers found themselves drawn to the lush, fertile rain forests and bountiful game inhabiting Kehjistan. But there was something else; Kehjistan's geography was rife with nodes of magical energies, and eventually those with innate, arcane abilities began to sense and recognize these forces, gathering in groups to settle these special areas. It was here that the original mage clans, the Vizjerei, the Ennead and the Ammuit, were founded. Unfortunately the history of Kehjistan is not a peaceful one, and the Mage Clan Wars that erupted nearly destroyed the clans.

Geographically, Kehjistan encompasses almost one-third of Sanctuary's eastern hemisphere. With an average rainfall of over four hundred inches per year, Kehjistan has the largest rainforests in the known world. This huge expanse of jungle feeds the Argentek River, which is the longest, widest river in Sanctuary. Hundreds of smaller rivers and tributaries twist and turn their way through the lush tropical forests until they finally unite with the mighty Argentek. Herbalists and alchemists revere the rainforest environment for its ecological diversity. Until recently, these sages would come from far and wide to study and collect the rare plants and animals that make their homes here. Now the jungle is far too dangerous to visit, let alone inhabit. Entire villages, even small cities have been wiped out. News has broken that Kurast, the current capital of Kehjistan, is now under siege by the powers of Hell, and is kept safe only through powerful magical barriers that even now begin to ebb and fade.

In ancient times, the great city of Kehjan was the capital city of the Eastern Kingdom. Though the ultimate fate of the once grand city remains unknown, there's much speculation about whether the lands were named after the city or vice-versa. it is also not clear where it was located, although the jungle environment suggests it was somewhere in the general region of Kurast.

Although implied to be simply a geographic region, it is revealed in Diablo III and related promotional materials that Kehjistan is actual an imperial state exercising control over both the lush jungles that dominate the core of the eastern continent as well as the drier desert to the north. The capital was located at Kurast for some time, until the elite of the city fled to Caldeum when Mephisto revealed himself. Emperor Hakan I soon followed and kept imperial power centered in Caldeum even when Mephisto fell, as he no longer trusted the Zakarum.