The Mantides is the Aelien name for a small caste that over time became the name for the whole race. It would be more accurate to call it the race of Wingers, as they were the ones the Mantides originated from.
Goddess Sangra was one of the first anthropomorphic Mantides. Long before the invasion of Aelion, the focus of her attention was on Terini, the neighbor planet of Terissa, which is the homeworld of the Mantides. The residents of Terini were a humanoid race, and so the goddess decided that she had to combine the ideals of both nations that she intended to rule. For that, she changed her appearance but remained the same inside. The beautiful face of the goddess was a mask that hid a monster.
Sangra succeeded: she won the admiration of Teriners and became the great goddess of the Mantides. Her confidants, inspired by her example, underwent the same transformation. “Anthropomorphic” now meant “godlike”. That was how the chosen caste was created - the Mantides, a bridge between the mortal and gods.