Primal

The Primals were the population of Reptilicus on Bryyo who scorned science and technology in all its forms. They were resentful of the Lords of Science when the population of Bryyo began to favor technology over their traditional ways of magic. When Sfimas denounced the Primals and their beliefs in the Royal City, an almost-catastrophic war ensued that nearly destroyed Bryyo. The few surviving Lords of Science were driven into hiding places, which "even the bravest Primals fear to tread". After all Lords were executed but one, they barbarically turned on each other. Some still lived and appear in Metroid Prime 3: Corruption, unfortunately hostile to Samus Aran because of their Phazon Fever infection.

The last living Lord of Science hid and built many Mogenar-Class War Golems, while also launching several machines into the air to cleanse the planet of its pollution and encountering an inhostile Prophetess who became his apprentice. After an accident in which their Fuel Gel supply exploded, their location was exposed, and the Primals approached. The last Lord instructed the prophetess to take his last records and flee to record them across Bryyo while he stood his ground.

A Bryyo Data entry says that after the last Lord of Science went into hiding, the Primals, who had become accustomed to war, had no one to hunt which led to them turning against each other and devolve mentally, becoming wild and aggressive. This contradicts the Reptilicus scan which states that the loss of higher brain function and aggression was caused by Phazon mutation.

As all remaining Science Lords were killed, it is safe to assume that the "technology" used by the Reptilicus is in fact the Primal's "magic", although they may have scavenged some older technology since they devolved.