KIACHTA, or KIAKHTA, a mercantile town of Siberia, and one of the chief centres of trade between Russia and China, is situated upon the Kiachta, an affluent of the Selenga, and on an elevated and barren expanse of country surrounded by mountains, in the Russian government of Transbaikal, about 280 miles southwest of the capital Tchita, and close to the Chinese frontier, in 50° 20' N. lat., 106° 40' E. long. Besides the lower town or Kiachta proper, the municipal jurisdiction comprises the fortified upper town of Troitskosaysk, about 2 miles to the north, and the settlement of Ust-Kiachta, 10 miles further distant. The upper town, which is substantially built, contains the public offices, barracks, a stone church, and many large warehouses, &T., and is the headquarters of the commandant of the Transbaikal Cossacks. The lower town, lying directly opposite to the Chinese emporium of Maimaichin, consists of several stores and about a hundred houses inhabited mostly by merchants. Prior to 1727 the trade of Kiachta was a Government monopoly, but from that year it was open to private merchants, and continued to improve until 1860, when the right of commercial intercourse was extended along the whole Russian Chinese frontier in conformity with the treaty of Pekin. The annual December fairs for which Kiaclita was formerly famous, and which were resorted to by merchants from a great distance, and also the regular commercial traffic passing through the town, have considerably fallen off since that date. The Russians exchange here leather, sheep-skins, furs, horns, woollen cloths, coarse linens, and cattle for teas, porcelain, rhubarb, manufactured silks, nankeens, and other Chinese produce. In 1873 the population, including Ust-Kiachta, was 9050.