Historic range map of the European bison (Bison bonasus): Historic range in green, relict populations in the 20th century in red
  Historic range
  relict populations in the 20th century
References:

M. Tokarska, C. Pertoldi, R. Kowalczuk, K. Perzanowski. Genetic status of the European bison Bison bonasus after extinction in the wild and subsequent recovery. Mammal Reviev, January 2011.
Own work
Leonid 2