It includes within its limits several large lakes, which receive rivers into their bosoms, and many of them having no outlets. The Azure Sea is the largest, lying at an altitude of 10,500 feet and overlooked by high mountains, which in winter are covered with snow, and in summer form an emerald frame that deepens the blueness of the water. It is over 200 miles in circuit, and its evaporation is replaced by the inflowing waters of eight large streams; one small islet contains a monastery, whose inmates are freed from their solitude only when the ice makes a bridge, as no boat is known to have floated on its salt water. The wide, moist plains on the east and west furnish pasturage for domestic and wild animals, and constant collisions occur between the tribes resorting there for food. The travels of Abbé Huc and Col. Prejevalsky furnish nearly all that is known concerning the productions and inhabitants of Koko-nor. The country is nominally divided into thirty-four banners, and its Chinese rulers reside at Síning, east of the lake; but they have more to do in defending themselves than in protecting their subjects. The whole country is occupied by the Tanguts of Tibetan origin, who are brigands by profession, and roam over the mountains around the headwaters of the Yangtsz’ and Yellow Rivers; by the Mohammedan Dunganis, who have latterly been nearly destroyed in their recent rebellion; and by tribes of Mongols under the various names of Eleuths, Kolos, Kalkas, Surgouths, and Koits. The Chinese maps are filled with names of various tribes, but their statistical accounts are as meagre of information as the maps are deficient in accurate and satisfactory delineations. The topographical features of this region are still imperfectly known, and its inhospitable climate is rendered more dangerous by man’s barbarity. High mountain masses alternate with narrow valleys and a few large depressions containing lakes; the country lying south of the Azure Sea, as far as Burmah, is exceedingly mountainous. West and southwest of the lake extends the plain of Tsaidam, which at a recent geological age has been the bed of a huge lake; it is now covered with morasses, shaking bogs, small rivers, and sheets of water--the most considerable of the latter being Lake Kara, in the extreme western portion. The saline argillaceous soil of this region is not adapted to vegetation. Large animals are scarce, due in part to the plague of insects which compels even the natives to retreat to the mountains with their herds during certain seasons. Its inhabitants are the same as those of Eastern Koko-nor; they are divided into five banners, and number about 1,000 _yurts_, or 5,000 souls.