The Green-scales, the Brown-scales, and the White-scales.

The Reptoids are a reptilian-humanoid species from hollow center of the earth.  They come in three varieties, Green-scales, the mountain and jungle dwellers, the Brown-scales, the inhabitants of the coasts, plains, and hills, and the White-scales, the mystics of the Reptoids, who dwell in burrows.  The Green-scales are the herders of woolly mammoths, who were taken by the Reptoids down into the center of Earth, and are skilled scouts and spear-throwers, they also fight and argue constantly with the Brown-scales.  The brown Reptoids are explorers and skilled warriors, who, long ago, discovered the surface world, and were amazed and frightened of the openness.  As time wore on, the Brown-scales, and some Green-scales, returned to the surface, and thought it good land, but they found another race, which they thought only existed in stories, the humans drove back the Reptoids, thinking them some kind of demonic brutes, which was the case with some Reptoids.  The White-scales, who lived with both Green and Brown Reptoids, foresaw it was unwise to mingle with the humans, but some, who could change there outward appearance, took the shapes of men and mixed with the human race.  The White-scales are the mystics of the Reptoids, who live in burrows throughout the hollow earth, and are seen in ceremonial garb and have decorated spears.  They are few, and their powers are not fully known, even by most other Reptoids, but through mating into Green and Brown-scales, the power of shape-changing has spread here and there, enabling the Reptoids to blend in among humans.  The technology of these reptilians is a mystery, they use spears and dart shooters, though they have some type of flying machine, or animal, that allows them to reach the surface, and any human that went down there, saw only primitive villages, but many people think they have hidden technology.