I1 is the Y-DNA hapolgroup associated with the Mesolithic (Stone Age) to early Chacolithic (Copper Age) dominant inhabitants of Europe. Some archeological cultures that have been postulated to belong to haplogroup I1:
Linear Pottery Culture (LBK) (5600-4240 BCE), Ertebølle culture (EBK) (5300-3950 BCE), Funnelbeaker culture (4000-2700 BCE) and Pitted Ware culture (3200-2300 BCE). Grooved Ware peoples, inhabitants of Skara Brae ~3100-2500BCE and builders of the Neolithic Megalith stone circles of Lewis (Callanish 2900-1000BCE) and Orkney (Stones of Stenness 3100BCE, Ring of Broadgar 2500-2000BCE, Ness of Broadgar 3500-2000 BCE , Maeshowe 2800BCE, etc)
I1 makes up 35% of the Y-DNA lines of modern Norway, and a majority of Fenno-Scandian Vikings. I1 is found in higher concentration on Lewis than Skye. Some subgroup SNPs such as I1-M253, P109, L1301, L1302, M307 are though to be Viking markers, but could just as easily be the aboriginal people of the Hebrides.