The Sylesi are a near-human species had several sub-species, each of which was distinguishable by the vestigial horns which ringed their heads. They were known for their ability to withstand great amounts of pain. The sylesi races were native to the planet Quatal III, but discovered the ability to travel through space only eight years after the humans discovered spaceflight. They quickly set out to colonize more hospitable worlds after a group of Human explorers provided them with the knowledge of spaceflight. The strong will and self-confidence of the sylesi led them to establish a number of colonies on remote worlds, each as loyal to its colony as to their homeworld.