335BC Macedonia is not Greek, 1821 AD Macedonia is Greek
The history of Macedonia is quite simple. Originally, the tiny ancient kingdom of Macedonia considered themselves Greek while the rest of Greece rejected them as outsiders, even trying to stop Alexander 1 from competing in the Olympics in the 100 meter dash, and probably synchronized swimming too. Then Greece conveniently decided that Macedonians were Greek, shortly after being conquered by Macedonia and declared to be Macedonians. At the same time, a large number of Paeonians, Illyrians, and Dardanians all decided that they were Macedonian as well, after being likewise conquered.
This was fortunate for them, as Rome's conquest of the region declared them as Macedonians for the next half dozen centuries. However, after Rome collapsed, slavic "Sklavine" peoples migrated into the region, leaving the former Roman province with an intermarriage of Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians and Sklavines, the former of wom who happily gave up their language in exchange for keeping their region name. But, under Byzantine rule, Macedonia magically moved east, with Bulgaria to its west! This left Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Now-Bulgarians to the west, and Neo-Macedonians to the east in present-day Bulgaria. Then Macedonia moved south again, leaving Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Now-Bulgarians to the west, Former-Thracians-Then-Macedonians-Now-Bulgarians, and former Thracians-Then-Macedonians-Then-Strymonians-Then-Macedonians-Again.
Now, it gets simpler. In the Ottoman era, Macedonia played a disappearing act. Hence, the Thracians-Then-Macedonians-Then-Strymonians-Then-Macedonians-Again became Thracians-Then-Macedonians-Then-Strymonians-Then-Macedonians-Again-Then-Bulgarians; they would later become Greeks, then Greek Macedonians again, but that's far in the future. The Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Now-Bulgarians in the present day TCFKATFYROM were now declared as Serbian, and hence became Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Then-Bulgarians-Then-Serbians.
The history gets even simpler from here on. As the Ottoman Empire collapsed, the residents briefly became Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Then-Bulgarians-Then-Serbians-Then-Bulgarians, before being captured by an independent Serbia and becoming Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Then-Bulgarians-Then-Serbians-Then-Bulgarians-Then-Serbians-Again. During World War II, they became Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Then-Bulgarians-Then-Serbians-Then-Bulgarians-Then-Serbians-Again-Then-Italian-Ruled-Albanians before Yugoslavia formed and Macedonia reappeared again, full of Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Then-Bulgarians-Then-Serbians-Then-Bulgarians-Then-Serbians-Again-Then-Italian-Ruled-Albanians-Then-Macedonian-Yugoslavians, and ultimately, after the breakup of Yugoslavia, Greek/Paeonian/Illyrian/Dardanian-Then-Macedonians-Intermarried-With-Sklavines-Then-Bulgarians-Then-Serbians-Then-Bulgarians-Then-Serbians-Again-Then-Italian-Ruled-Albanians-Then-Macedonian-Yugoslavians-Then-Macedonians.
Today, the independent nation simply shortens this ethnic identity to "Macedonians". Sadly, this simple and uncomplicated history has somehow lead to an international identity controversy.
Read more comic relief of Macedonia: