On the other hand, I2a1b1 (P41.2) is typical of the South Slavic populations, being highest in Bosnia-Herzegovina (>50%). Haplogroup I2a2 is also commonly found in north-eastern Italians. There is also a high concentration of I2a2a in the Moldavian region of Romania, Moldova and western Ukraine. According to original studies, Hg I2a2 was believed to have arisen in the west Balkans sometime after the LGM, subsequently spreading from the Balkans through Central Russian Plain. Recently, Ken Nordtvedt has split I2a2 into two clades – N (northern) and S (southern), in relation where they arose compared to Danube river. He proposes that N is slightly older than S. He recalculated the age of I2a2 to be ~ 2550 years and proposed that the current distribution is explained by a Slavic expansion from the area north-east of the Carpathians.