Lewis & Short

Bīsaltae, ārum, m., = Βισάλται, a Thracian people on the Strymon, Verg. G. 3, 461; Liv. 45, 29, 7; 45, 30, 3; Plin. 4, 10, 17, § 38.
Hence the country they inhabited was called Bīsaltĭca, Liv. 45, 29, 6, or Bī-saltia, Gell. 16, 15 (Βισαλτία, Thuc.).