The zoogeographic subdivision of the desert areas of the world reflects the variation in the taxonomic composition of their rodent faunas. In the context of this chapter, we analyze and consider rodent distribution at the family level. The only exception is the Muridae which will be considered at the level of subfamily. This is because of the extremely high generic and species richness of murids and the distinct morphological and ecological specialization of most subfamilies. In addition, the taxonomic rank of the murid subfamilies is contestable and most of them are often considered as separate families within the superfamily Muroidea (see review in Carleton and Musser 1984).