Biysk (bēsk) [key], city (1989 pop. 233,000), S central Siberian Russia, on the Biya River. A port and the terminus of a branch of the Turkistan-Siberia RR, Biysk manufactures food-processing equipment and was the site of a large defense plant during the Soviet era. It is linked by highway to Mongolia and is a trading center for agricultural goods. The city was founded as a fortress in 1709; its name is sometimes transliterated Bisk or Biisk.