BORISOGLYEBSK, a town in the south of the Tambov province of the Russian Socialist Federal Soviet Republic. Pop. (1926) 39,062. It was founded in 1646 as a frontier defence of Muscovy against the Crimean Tatars and in 1696 was surrounded by wooden fortifications. It has annual fairs and trades in grain (and has an elevator), wool, cattle and leather, and has iron cast ing, leather, tallow and brick-making industries.