Roslagen

Folklands in Svitjod (Uppland/Gästrikland)
red = Tiunda
cyan = Attunda
yellow = Roden / Roslagen
green = Fjärdhundra

The coastline has changed considerably in the last millennium due to post-glacial rebound. Originally there was a sea bay coming in from the north all the way into Uppsala. Roslagen is the modern name the area which roughly corresponds to that which was called Roden in the Middle Ages .

Roslagen is the name of the coastal areas of Uppland province in Sweden, which also constitutes the northern part of the Stockholm archipelago.

Historically, it was the name for all the coastal areas of the Baltic Sea, including the eastern parts of lake Mälaren, belonging to Svealand. The name is derived from Roden, which is the coastal equivalent to inland Hundreds. When the king would issue a call to leidang, the Viking Age equivalent of military conscript service, a Roden district was responsible for raising a number of ships for the leidang navy.

Etymologically, Roden, or Roslagen, is the source of the Finnish and Estonian names for Sweden: Ruotsi and Rootsi.

The area also gives its name to the endangered domesticated Roslag sheep, which originated from the area centuries ago.