Complex sentence: The Southern Provinces or Moroccan Sahara are the Moroccan names for Western Sahara, referring to the former Spanish provinces of Río de Oro and Saguia el-Hamra.
Split into simpler sentences: The Southern Provinces or Moroccan Sahara are the Moroccan names for Western Sahara. The provinces in question are Río de Oro and Saguia el-Hamra.