Complex sentence: The Anla-shok (Rangers) were originally created by Valen during the First Shadow War, when the 3 castes refused to work with him to defeat the Shadows so he went outside the caste system.
Split into simpler sentences: The Anla-shok (Rangers) were originally created by Valen during the First Shadow War. When the 3 castes refused to work with him to defeat the Shadows, he went outside the caste system.