The Mostari are a species of humanoid beings native to the Mostari homeworld. The Mostari have four arms and four horns on their head.
Before Harley Shepherd visited their planet, it was close to chaos among the Mostari. They were starving and their villages were feuding with each other. He introduced plows, crop rotation, medicine, as well as adapted the English alphabet and taught them to read.
Shepherd taught them about laws and how to cooperate. The Mostari chose him as their leader, and he led them until Major Gus Bonner and his team discovered that he had become somewhat corrupt with power. (INF: "Mentor")