I can only laugh about this. Slavs came to that area almost 1000 years after Alexander. He was a Greek. This and nothing else. When he ruled this area, Slavs were in some asian steppes. Thats a matter of fact.
Slavs came around the year 600 after christ in the area and the Byzanthine Empire ignored them first.
en.wikipedia.org/wiki/Sclaveni
It was Emperor Maurikios who then ended their presence and stopped them with a campaign
en.wikipedia.org/wiki/Maurice%27s_Balkan_campaigns
I can understad why some slavs want steal greek history. Its same reason why some american africans try to steal egyptian history.
They dont have a grandpast like we have and this hurts i guess so they try to make up stuff.
And FYROM learned the hard way. Since almost 30 years Greece blocks them from any development. They want be member of EU or maybe start membership process and get support. Greece blocks it.
They want become member of NATO because they fear Russian influence. Greece blocks it.
So...
@kaprys
You want see the reaction of an arrogant greek to this?

Here it is :D

Oh and Crow. Sciece says we have same DNA as our ancestors had 3000 years before :)
sciencemag.org/news/2017/08/greeks-really-do-have-near-mythical-origins-ancient-dna-reveals
Now, ancient DNA suggests that living Greeks are indeed the descendants of Mycenaeans, with only a small proportion of DNA from later migrations to Greece. And the Mycenaeans themselves were closely related to the earlier Minoans, the study reveals, another great civilization that flourished on the island of Crete from 2600 B.C.E. to 1400 B.C.E. (named for the mythical King Minos).
We simply are the best thing.
Oh and this isnt about tourism. This is about honor.
We dont want some beggars and gypsies stain our ancestry. Slavs came to that region late and have zero connection to us Hellenes.