Traditionally, our Ancestry Composition report compared customers’ data to 31 different populations, allowing 23andMe to report the percentage of DNA that came from those regions. This helped connect individuals to their ancestry back 500 years before the advent of modern migration.
Source: https://blog.23andme.COM/articles/23andme-updates-ancestry-composition
As explanation for the feeble minded, this means that the commercial DNA services do not take into account ancient migrations, nor even migrations in medieval times.
If you want to know where Jews were living in the Middle Ages that you need to find out more about Jewish migrations over the last 2000 years. But then wilful ignorance is your speciality.