Essentialism has been hypothesized to be associated with intergroup hostility. However, it is unclear whether ethnic essentialism is a feature of human social cognition across a range of socio-ecological settings and what the causal direction of its association with intergroup hostility is. Using “switched at birth” vignettes, we assessed the extent to which Turkana pastoralist warriors have essentialist beliefs about themselves and the neighboring Toposa ethnic group in South Sudan who engage in mutually lethal cattle raids. We found that only four of 162 (2.5%) Turkana surveyed expressed essentialist beliefs about themselves and the Toposa. The four participants who expressed essentialist beliefs did not exhibit unusual combat-related behavior and attitudes toward the outgroup. Specifically, they were, with one exception, no different than non-essentialist survey respondents in their levels of combat exposure and killing of enemies in combat. The cultural similarity between the Toposa and Turkana, a common origin story, cross-group adoption and cross-border friendships may explain the Turkana’s low frequency of essentialist beliefs despite widespread lethal violence. The results suggest that ethnic essentialism may not be a necessary ideology for engaging in intergroup hostilities, and lethal intergroup interactions need not lead to the development of essentialist beliefs.