I t is a lofty and for the most part a rainless tableland traversed by numerous mountain-ranges divided from each other by flat plains and falling away toward the centre, which is a desert white with salt scurf or dun with powdery dust. The mountains are highest round the edges of the tableland and intercept most of the rainfall. Some moisture, however, finds its way even into the rainless region, where it gathers during winter on the higher hills in the form of snow. This snow-water is carefully husbanded, and distributed by means of underground water-courses. The interior is, however, drying up, and city, village, and cultivated field are being gradually overwhelmed in dust and shifting sands.