(J. F. C. F.) also called Tuz-kul or salt lake, owing to its brackish waters, and by the Kalmucks Temurtu-nor (iron lake), a lake in the Kirghiz A.S.S.R. (q.v.) lying in a deep basin, appar ently of tectonic origin, 5,400 ft. above sea-level. It extends from 76° io' E. to 78° 2' E., and has a length of 115 m. from W.S.W. to E.N.E., and a breadth of 38 m. ; its area is estimated at 2,23o sq.m. The name is Kirghiz for "warm lake" in reference to the fact that though ice may form occasionally, the surface of the lake is never completely frozen over. Issyk-kul lies between two westward running spurs of the Tian Shan mountains, the Kunghei Ala-tau range to the north, which rises on an average 8,000 ft. above the level of the lake, with peaks reaching 13,000 ft., and the snow clad Terskei Ala-tau range which skirts the south of the lake at a distance of 5 to 13 m. and rises 6,000 to 9,00o ft. above its level, with peaks reaching 15 to 18,000 ft. The passes over the Terskei lie at great altitudes, the Barskoun (12,00o ft.), the Suka or Sauka (11,65o ft.) and the Jauku (14,00o ft.). The Sauka, linking northwards with Karakol, the eastern stage for steamer communication with the west of the lake, from which a comparatively easy route leads to the railhead at Tokmak, is most used, since it links south with the Ak-su oasis by the Akbel pass (I 2,000 ft.) and the Bedel pass (12,40o ft.). Another route, involving a steep climb of 12,000 ft. over the Muzart Pass on the east of Khan-tengri, leads to the Tekes river.
The narrow plain which fringes the lake extends inland for 46 m. to the east and then rises to the Santash range, 5,97o ft. above the level of the lake, which forms a link between the Terskei Ala tau and the Kunghei Ala-tau. A route from the east of the lake crosses this ridge, goes along the valley of the Tegen river, and crosses the Temur-lik-tau range to Kulja in Chinese Turkestan. There is an abundance of blossom, especially at the eastern end of the lake where bee-keeping is profitable, over Boo tons of honey being exported per annum. There are few trees, except in the valleys of the streams entering the lakes. Numerous small streams reach the lake from the mountain slopes, the two chief being the Tyub and Dzhargalan from the east. The Chu river rises in several streams to the west of the lake and approaches the western extremity very closely in a curve which it takes before flowing north-west to lose itself in the desert ; it is incorrectly shown on some maps as draining from Lake Issyk-kul. A marsh
extends between the bend of the Chu and the lake, and a tiny stream drains from this marsh into Issyk-kul. Issyk-kul probably at one time drained through the Baum gorge at the north-west extremity of the lake, through which the route now goes to Tok mak and the Russian settlements on the fertile loess strip extend ing to Frunze. The present level of the lake is lower than in former times, and sandy marshes overgrown with reeds, the haunts of the wild boar and the tiger, have spread on the sites formerly occupied by the lake. Fish, especially carp, abound in the lake; its waters are too salt to provide drinking water. The soils on the shore of the lake are sandy, but in a few places there are fertile clayey patches. The nomad herdsmen pasture their flocks in the Issyk-kul valley in winter and on the high alpine meadows in summer.
Along the narrow route by the southern shores of the lake, passed the tribes driven westward by the Huns, notably the Indo-Scythian Yue-chi (q.v.), and the blue-eyed and fair-haired Uzuns or Ussuns from Central Asia at the end of the 2nd century B.C. The former .passed further west, but the latter settled in the valley and built the town of Chi-gu near the Tyub river, which still existed in the 5th century. The rude stone images of the Uzuns are sometimes washed up from the lake and are of a type distinct from those of the Kalmucks or Kirghiz; a huge copper cauldron of the Uzuns was washed ashore in 1842. The Uzuns disappear from history after the 5th century, but the fair-haired, blue-eyed, straight-nosed element sometimes met with among the Kirghiz of the Issyk-kul region indicates that they were probably absorbed by these tribes. The valley is at present occupied by the On, (right or east) section of the Kara-Kirghiz, with Russian settlements at the eastern end of the lake. Hsuan tsang (q.v.) the Chinese Buddhist pilgrim passed south of Issyk kul in the seventh century and has left a description of the region. In the early 14th century Nestorian Christians founded a monastery on the northern shores of the lake, indicated on the Catalan map of 1374. The famous Russian explorer Nikolai Przhevalsky (q.v.) died at Karakol in 1889, and for a time the town bore his name. The region was annexed to Russia in 1864.