Tylöskog is a deep and extensive
forest between the agricultural plains of the counties of
Närke and
Östergötland in southeast
Sweden. Together with
Tiveden to its west and
Kolmården to its east, it famously constituted the wartorn frontier between the
Swedes in
Svealand and the
Geats in
Götaland during the formation of the
Swedish nation in the 13th century. The name is derived from
Tylö, a small locality in the forest (the suffix
skog meaning
forest in
Swedish).