Macedonia is Greek

However remember that from the seventh century onward since the Balcan wars Macedonia was horribly poliethnic. Macedonian Greeks constituted only 24 % of the population, that is in Rumluki, south-western Macedonia, Chalkidiki and Darnakochoria, cities like Serres, Naussa, Gidas... All the rest was populated by 35 % of Slavs, punctured by big enclaves of Turks (27%), Vlachs etc. Thessaloniki was neither Greek, nor Slavic nor Turkish, from the XV century it was a Jewish city (Jews were 41 % of the population, if not more, since the muslims of Jewish origin were not classified as Jews).

The majority of toponyms was definitely non-Greek and mainly Slavic by origin. Even in Rumluki we had a handful of Slavic toponyms (like Kutlesh, Barbesh, Kalliani etc.), left by Slavic tribe of Sagudates which lived there alongside with Greeks, before they were expelled to Bithynia by Bisantines