Kazaria was actually south of what is now Khazakhstan although its borders grew and shrank over 400 years. More like present Turkmenistan, Uzbekistan, and Kyrgistan. However all of the area was overrun back and forth by nomad tribes, so genetically a fair bit of mixing and similar cultures. I recommend a book called The Thirteenth Tribe by Alfred Koestler about these people and the Ashkenazi. Those nomad tribes were a tough, dirty, ornery lot all around.