Complex sentence: Others, after having been excluded from the tribe for two decades in the twentieth century and given the continuing citizenship struggle, have become ambivalent about their ties and no longer consider identifying as Cherokee as necessary to their personal identity.
Split into simpler sentences: Others, after having been excluded from the tribe for two decades in the twentieth century and given the continuing citizenship struggle, have become ambivalent about their ties. They no longer consider identifying as Cherokee as necessary to their personal identity.