I think Taylor Sheridan might be confusing Karl Marx's own interest in the Iroquois with interest in the Lakota. In brief, shortly before Marx's death, a man named Lewis Morgan published a work called Houses and House-Life of the American Aborigines that argued that the Iroquois essentially lived by the virtues of communism that Marx had exposed. Marx, in turn, developed a theory known as "primitive communism." According to Marx, all hunter-gatherer societies began as egalitarian societies that exhibited the qualities of "primitive communism." In these societies, the "clan" as a whole trumped what we would now call the nuclear family, as people took care of everyone's children and not only their own. Thus the rise of the Western concept of the "family" corresponded with the rise of capitalism in a sense (Engels published this analysis at length in the work The Origin of the Family, Private Property and the State). It is important to note, however, that Marx (and Engels) did not mean that these societies represented the communism that they predicted would rise in highly industrialized societies. Instead, this "primitive communism" was evidence that "communism" was the natural and inevitable end to the development of humankind. It is also important to note as well that scientific knowledge of hunter-gatherer societies has come a long way since the days of Marx and Engels and that Marx's theory regarding hunter-gatherer societies is not foundational to the field in the same way his theories of class and economics are to other fields.