The Bartians (also Barthi, Barthoni, Bartens, or Barti) were an Old Prussian tribe who were among the last natives following a pre-Christian religion before the Northern Crusades forced their conversion to Christianity at the cost of a high percentage of the native population. They lived in Bartia (also Bartenland or Barthonia), a territory that stretched from the middle and lower flow of Łyna river, by the Liwna river, and Lake Mamry, up to the Galindian woods. The territory is quite precisely known from description in Chronicon terrae Prussiae, dated 1326.
The same description mentions two provinces, the Major Barta and the Minor Barta. The territory was quite densely populated, as confirmed by abundant archeological findings. Before the wars with the Teutonic Knights, the population was estimated to be at 17,000.