Complex sentence: The Cordillera peoples are a founding Member of UNPO, represented through the Cordillera Peoples' Alliance (CPA), which is a federation of organizations of the indigenous peoples of the Cordillera.
Split into simpler sentences: The Cordillera peoples are a founding Member of UNPO. They are represented by the Cordillera Peoples' Alliance (CPA), which is a federation of organizations of the indigenous peoples of the Cordillera.