The age of YSTR variation for the I-M223 subclade is 13.2±2.7 kya and 12.3±3.1 kya. I-M223 has a peak in Germany and another in eastern Sweden, but also appears in Romania/Moldova, Russia, Greece, Italy and around the Black Sea. Haplogroup I2a2a has been found in over 4% of the population only in Germany, the Netherlands, Belgium, Denmark, England (excluding Cornwall), Scotland, and the southern tips of Sweden and Norway in Northwest Europe; the provinces of Normandy, Maine, Anjou, and Perche in northwestern France; the province of Provence in southeastern France; the regions of Tuscany, Umbria, and Latium in Italy; Moldavia and the area around Russia's Ryazan Oblast and Republic of Mordovia in Eastern Europe. Of historical note, both haplogroups I-M253 and I-M223 appear at a low frequency in the historical regions of Bithynia and Galatia in Turkey, possibly descendants of the Varangians, who are historically recorded to have invided those parts of Anatolia from the 9th to 11th centuries. They ventured southwards along the rivers of Eastern Europe, connecting Scandinavia with Constantinople and Byzantine Empire. Haplogroup I2a2a also occurs among approximately 1% of the Sardinians. The subclade divergence for M223 occurred 14.6±3.8 kya (Rootsi 2004).
Haplogroup I-M223 can be further subdivided in several subclades designated in the Y2012 ISOGG tree as follows: Haplogroup I-M223* with no further known polymorphisms, Haplogroup I-M284 defined by M284 polymorphism and including an undergroup Haplogroup I-L126 reserved for individuals derived for the L126/S165, L137/S166 polymorphisms, Haplogroup I-L701 associated with L701 polymorphism, and Haplogroup I-Z161 denoting individuals derived for the Z161 polymorphism.
I-Z161 is further subdivided into I-Z161* with no known polymorphisms, I-L801 defined by L801 polymorphism, and I-L623 designated by L623 polymorphism. I-L801 (L801) is further subdivided into I-L801* and I-P95, the latter being associated with the P95 polymorphism. Recently, several new SNPs have been identified including Z76, which is believed to be phyloequivalent with L801, and L812 Roots polymorphism. The recently added L801 Continental is estimated to be around 3000 years old. Other SNPs currently being investigated for placement in the tree include: Z78, Z79, Z190, and L1198, all of which are believed to be downstream of both Z161 and L801.