What is "shvarn"

Shvarn or Shvarno Daniilovich (, ; c. 1230 – c. 1269), was the knyaz of western parts of Galicia (1264 – c. 1269) and Grand Duke of Lithuania (1267 – c. 1269). An influential leader, he became involved in internal struggles of power within neighboring Grand Duchy of Lithuania. He also held the town of Kholm (modern Chełm, Poland) in his domain.