the khazar is an area close to russia and armenia that in the year 800 converted from idol worship to judiasim to protect themselves from the chrisitan invasion and muslim invasion....these jews dont have any connection to the jews of arabia.....these jews made up the jews of europe in later centuries and had thier language as yeedish not hebrew.....most of them moved to poland from khazaria after the russians destroyed their kingdom in khazar.......
a few arab travelers gave us a lot of description about the khazaria kingdom...a good book to read about them is the " THE THIRTEENTH TRIBE" iforgot the author but it is a good book