Historically, the Turkish nation was ridiculously multi-ethnic though, wasn't it? You have Altai, Chuvash, Kyrgyz, actual Turcomen, who knows how many others. "I'm proud of my Turkish heritage and have been since I obtained it last week".

And yeah, Rome died hard in the East. No denying that. But it's worth noting they had, century after century, so many opportunities to ally and rebirth with other peoples - Syrians, Macedonians, Bulgars, Russians, French - only to stab them right in the kidneys at the absolute worst time. Byzantium was like if you took Black Adder and made him into an entire country. Or Cersei Lannister, in the bad years.