The Second Swedish Crusade was a military expedition by the Kingdom of Sweden into Tavastia c. 1249–1250 as described by the Erikskrönikan. As described by the Erikskrönikan, the Swedes defeated the Tavastians under the leadership of Birger Jarl.

Swedish pre-history ends around 800 AD, when the Viking Age begins and written sources are available. The Viking Age lasted until the mid-11th century. Scandinavia was formally Christianized by 1100 AD. The period 1050 to 1350—when the Black Death struck Europe—is considered the Older Middle Ages. The Kalmar Union between the Scandinavian countries was established in 1397 and lasted until King Gustav Vasa ended it upon seizing power. The period 1350 to 1523 – when king Gustav Vasa, who led the unification of Sweden in the Swedish War of Liberation, was crowned – is considered the Younger Middle Ages. During these centuries, Sweden gradually consolidated as a single nation.