The most ancient and powerful race in the galaxy, the Protoss possess a highly structured society based on the preservation of their way of thinking. Highly intelligent and gifted with great psionic powers, they nevertheless suffer from a certain inflexibility that makes them extremely difficult to work with. Originally the Protoss were divided into several warring tribes, but they were united by a single Protoss warrior/philosopher, Adun. He is apparently responsible for strengthening the psionic racial link that all Protoss share, and he developed the Khala,  
a strict religion, philosophy, and social structure. Under the Khala, the Protoss have mostly abandoned their tribal lines and divided into three castes: Khalai, artisans and inventors; Templar, warriors and explorers; and Judicator, administrators and leaders.