The Pomeranians, first mentioned as such in the 10th century, were a West Slavic tribe, which from the 5th to the 6th centuries had settled at the shore of the Baltic Sea between the mouths of the Oder and Vistula Rivers. They spoke the Pomeranian language that belonged to the Lechitic languages, a branch of the West Slavic language family.

Kashubian or Cassubian is a West Slavic language belonging to the Lechitic subgroup along with Polish and Silesian. Although often classified as a language in its own right, it is sometimes viewed as a dialect of Polish.