The Tefra Pass is a volcanic fissure that slices through the Ghaltri Range skirting the southern edge of Crown Rimwald. It is volcanically active and comprised of geisers, strange volcanic formations, labyrinthine lava tubes, and fields of volcanic glass. All of these making for a daunting, maze-like passage. This is one of the only Crowns in the Alamastran Empire to be ruled by a non-human race, and the only to be ruled by a non-demihuman race. The Crown of Tefra Pass is ruled by a tribe of minor infernals, which splintered from the Infernal Legions during one of the Great Upheavals at Rivenwar. This tribe, known as the Tefra, is comprised mainly of Dark Jinn, Ifriti, and reportedly even a Fury. They are ruled by a Suzerain Jinn, known as Shurush, who seems to represent both masculine and feminine aspects of the Infernal Pageant. The Tefra Tribe has remained strictly neutral in all conflicts. However, during the last Upheaval the signed a concordat with the High Throne, and incorporated as a Crown of the Empire, perhaps one of the smallest. They were charged with establishing an Imperial Highway through their realm, collecting the tollage, and keeping the peace in exchange for autonomy and exemption from Imperial service. The Crown tribute comes from the tollage collected. Shurush is recongnized as the Lord Magnate of the Crown and the Tefra Tribe its subjects. It is not entirely clear how the Tefra organize themselves internally, as they do not conform to the ridged hierarchy of the Infernal Legions from which they splintered.

On rare occasions Tefra have journeyed beyond their homeland, but many seem to be bound to this pass. The most famous example is the ifriti, known by his companions (imanginatively) as Tephra. He participated in a bid to restore House Starcrest to the High Throne. One that ultimately failed in that end, but succeeded in preemptively turning back an invasion by the Infernal Legions via the Rivenwar Rift.

Little is known about the Tefra way of life, religion, or social organization. They still practice infernal magic, but otherwise seem to be of an entirely different stock from other minor infernals encountered by the Alamastrans. They are strictly of true neutral alignment, with no propensity to any evil alignment. They seem to be entirely divorced from the command structure and culture of the Infernal Legions, in fact they seem to be entirely forgotten by them.

When asked by scholars, the Tefra are less than forthcoming, but also seem not to have a full explanation for themselves. Shurush is recorded by an immanent traveler as saying they are attracted to and protected by the power of the pass itself as a geothermic and volcanic hotspot, but this seems an partial explanation at best.