What has been historically known for years has now, like so much of Jewish history, been proven. There are genetic links that can be shown via scientific evidence between the Jews who settled in Europe, Ashkenazim, and those who settled in the Mediterranean regions, the Sefardim.
Ashkenaz is the Hebrew word for Germany while Sefarad is the word for Spain. Jews thrived in both countries until they were exterminated in Germany in the twentieth century and expelled in 1492 from Spain. When they were expelled from Israel by the Romans in 70AD they made their way to these two regions.