Cultural event
Bradley MacBride has gained influence in the Ozarks and made promises to re-unify was used to be the Plains Commonwealth into a singular state. Assuming they knew about MacBride and the Enclave's arrival, the locals were on-board with unification. No community or tribe was able to gain power over the others in the short time since the bombs fell, and many enjoyed hearing MacBride's ideas of re-making America into a global superpower, starting with the Second Plains Commonwealth.
Any groups that dissented MacBride or were too skeptical of his promises were deemed Communists and either forced from the region, or killed outright, usually with help from supporters. Some of these skeptics were able to run and hide in the ruins of the Silver Dollar City theme park.