http://www.haaretz.com/life/science-medicine/.premium-1.614893 A model based on the genetic sequencing of 128 Ashkenazi Jews concludes that todays Ashkenazim descend from the fusion of European and Middle-Eastern Jews during the medieval era, between 600 to 800 years ago. The math also indicates that todays sprawling community of Ashkenazi Jews there are more than 10 million around the world derived from just 350 people or so. That previously postulated population bottleneck a drastic reduction in population size occurred between 25 to 32 generations ago, the scientists say. this might corrolate with the idea that the Ashkenazi Jews are descended from the Khazars, who it was proposed that their royal family converted to Judaism. And a royal family of 350 persons isn't too hard to fathom.