The answer is the indians were never friends with each other to begin with. Tribes were/are historically long-term enemies with each other. this whole idea that they all got along swell and wonderfully until white guys got here (actually came back, dna evidence shows we were here before the asians came over the aleutian bridge), is just bull puckey.
Or at least stop weakening yourselves in the process of trying to defeat that threat.
In my mind, there is no bigger threat than the communists.