Turkey and Greece have been dancing around each other for centuries.

There was quite a lengthy period of time (some 370 years, from the 1450s to the 1820s) where much of what is now Greece was under Ottoman rule. Your picture looks to be smack in the middle of this period.

It was only in the early 20th century, in 1923, that a mass population swap involving several million people took place, to incredible demographic effect in both countries - Orthodox Christians from Anatolia poured into Greece, and Muslims from Greece poured into the freshly depopulated lands in Turkey. Weirdly, religious affiliation seems to have been the only thing they looked at. Not ethnic background. Not language. Many of the deported and denaturalised Muslims were either Greek or Albanian, specifically pinpointed as NOT being of Turkish descent. Nevertheless they were sent to Turkey. Many of the deported and denaturalised Christians either did not speak Greek at all outside of church settings, or spoke a dialect (like Pontic or Cappadocian) that their new neighbours found completely incomprehensible. Nevertheless they were sent to Greece. The whole thing was a huge mess, deeply traumatic for the people involved and had remarkable effects on the demographics - the pre-swap Christian population of Turkey was ten times the size of the post-swap one, and they lost huge swathes of their merchant and urban professional population at a sweep.

Basically, they’re grouped together because they are kin. They’ve intermixed for centuries, and it would be pointless trying to separate them out now.