You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
alternatehistory.com
Is this actually possible? Do you need a POD where some Turkic tribes are more drawn to Orthodox Christianity and speaking Medieval Greek rather than Islam and speaking Persian or Turkic languages and actually integrate into Byzantine Empire. I know there were Slavic and Armenian dynasties ruling over the Byzantine Empire. I would imagine the Byzantine Empire at this point would only be Greece and Asia Minor.