To understand tieflings one must first understand the term Planetouched. Planetouched was a general term used to describe mortal creatures whose lineages traced back to an outsider of some kind, causing them some unusual characteristics that persisted in the bloodline for several generations. Outsiders typically being celestials, fiends, and even sometimes outer gods. Planetouched were not as dramatically different as a true hybrid (i.e. a half-celestial or half-fiend) would be. The most common types of planetouched were tieflings and aasimar. However, there were no "typical" planetouched, as the different types generally lacked cultures of their own and instead adopted the culture they were born into. Below is a list I've compiled of all known planetouched races I have come to study.

• Aasimar were descended from celestials.
• Axani were descended from lawful outsiders.
• Azerblood were descended from shield dwarves and azers.
• Cansin were descended from chaotic outsiders.
• Celadrin were descended from elves and celestial eladrin.
• Chaonds were descended from slaadi.
• D'hin'ni were descended from lightfoot halflings and djinn.
• Genasi and para-genasi were descended from elemental creatures, usually genies.
• Gloamings were descended from inhabitants of the Plane of Shadow.
• Mechanatrixes were descended from the clockwork beings that resided in Mechanus.
• Shadowswyfts were descended from creatures from the Plane of Shadow.
• Shyfts were descended from beings from the Ethereal Plane.
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• Zenythris were descended from an unknown race of lawful outsiders.
• Part-fiends were among the most common planetouched, with many different types deriving from specific mortal, and in some cases fiendish, races.
  • Tieflings were perhaps the most common and well-known planetouched, descending from the mixing of humans and fiends.
  • Baphitaurs were a combination of human, minotaur, ghour, and goristro magically created by Netherese wizards.
  • Draegloths were the half-fiend offspring of drow and glabrezu.
  • Durzagon were the half-fiend offspring of duergar and devils.
  • Fey'ri were descended from elves and demons.
  • Maeluth were descended from dwarves and devils.
  • Mur-zhagul were descended from trolls and demons.
  • Tanarukk were descended from orcs and fiends.
  • Wisplings were descended from halflings and demons.
  • Worghest were descended from goblins and barghests.

The following Chapter will focus on Tieflings and their variants being that they are the most common of the planetouched, to the point of their variants nearly being sub-species of their own.