Haplogroup I1 is the most common Northern Europe I sublcade in Northern Europe, according to Eupedia.com. Haplogroup I1 represents over 30 percent of the male Y chromosome in Scandinavia and Finland, where it is found the most. It is associated with Norse ancestry.
Historically, haplogroup I1 is considered the only major haplogroup that originated in Europe. The men who are a part of haplogroup I1 are descended from one ancestor who lived over 8,000 years ago. It is thought to have been developed from the IJ haplogroup. Haplogroup I1 is present in all places that were invaded by Vikings and the Germanic tribes.