Viking raid warfare and tactics
Vikings were members of tribes, originally from Scandinavia, of Norse ancestry, who gained a reputation for their raids and piracy in many parts of Europe, especially England, Ireland, and Frankish territories. The term "Viking Age" refers to the period roughly from 793 AD to the late 11th century in Europe. In this era Viking activity started with raids on Christian lands in England and eventually expanded to mainland Europe, including parts of present-day Russia. While maritime battles were rare, Viking bands proved very successful in raiding coastal towns and monasteries due to their efficient warships, and intimidating war tactics, skillful hand-to-hand combat, and fearlessness. What started as Viking raids on small towns transformed into the establishment of important agricultural spaces and commercial trading-hubs across Europe through rudimentary colonization. Vikings' tactics in warfare gave them an enormous advantage in successfully raiding (and later colonizing), despite their small population in comparison to that of their enemies.
History of Finland
Contact between Sweden and what is now Finland was considerable even during pre-Christian times; the Vikings were known to the Finns due to their participation in both commerce and plundering. There is possible evidence of Viking settlement in the Finnish mainland. The Åland Islands probably had Swedish settlement during the Viking Period. However, some scholars claim that the archipelago was deserted during the 11th century.
According to the archaeological finds, Christianity gained a foothold in Finland during the 11th century. According to the very few written documents that have survived, the church in Finland was still in its early development in the 12th century. Later medieval legends from late 13th century describe Swedish attempts to conquer and Christianize Finland sometime in the mid-1150s.