One of the things that has stood out for me as I read Shelley's book on the Western Sahara is just how small the indigenous population of the territory is in comparison to Morocco or even Mauritania. There are no exact census data, but the estimates all point to a very small population especially given the geographic size of Western Sahara. Shelley puts the number of indigenous Sahrawis at 90,000 in the territory and the number of Moroccan settlers as many as 300,000 plus 160,000 soldiers. Including the Sahrawi refugees and others outside the territory may have boosted the indigenous population up to 250,000. Since that time the total population of Western Sahara is estimated to have exceeded 500,000. But, finding a breakdown between the indigenous population and the settlers has eluded me. This demographic reality means that Morocco has successfully swamped the territory with its own citizens and made the Sahrawis a rather small minority, about 25%, in their own country. Given the unreliable nature of all the population figures on Western Sahara, please feel to add any corrections, updates, or other information you might have in the comments.
Note: I have updated the post with more accurate information since yesterday.