The Gorma Tribe are the antagonists of the 1993 Super Sentai series, Gosei Sentai Dairanger (Five Star Squadron Generation Rangers). They are shown to be an old tribe, coming back into modern society to destroy humanity. They themselves are humans possessing You Ryoku (Demon Power), and have the ability to change their appearance.
8,000 years ago in ancient China, the mighty Daos Empire was made of three tribes: the Dai Tribe (which the Dairangers are descended from), the Gorma Tribe and the Shurs Tribe (who never get explained properly). The three tribes lived in harmony with one another, until the Gorma Tribe decided to destroy the other two. However, a small band of fearless warriors faced the Gorma Tribe and cast them out. Their leader, Gorma Emperor XV, was sealed in Hell, where he was meant to remain for all eternity.
And yet, the Gorma Tribe resurfaced, which forms the events of the TV series.
The Gorma Triumvirate, consisting of Shadam, Gara and Zydos, spearhead the return of the Gorma into our world. However, they appear to have overlooked the appearance of the Dairangers (the decedents of the Dai Tribe warriors who defeated them in battle). Possessing Ki Ryoku (Star Power), the enigmatic Doushi Kaku gathered the team together, and told them of who they were to fight. Then began the war which made up the TV series.
However, it's revealed that most of the higher aristocracy in the Gorma Tribe had died before the show even began, as they'd been killed by Shadam and replaced with clay copies, in order to facilitate his plan to become Gorma Emperor XVI and rule the world. And yet, at the end of the series, it was revealed Shadam himself was made of clay, so it was never known what happened to the real Shadam, or who made the clay copies.