One may see at Teheran’s museum in Iran a stone with an inscription dated back to 513 BC that lists the European lands occupied by Great (Persian) King at that time. Amongst them there is a line “Yauna Takabara” that is Ionians with a helmet like a buckler. It is very easy to recognize that helmet in Macedonian coins. At that time Persians hadn’t Thessaly or any other southern Greek land, so the inscription refers to the Macedonians. The point is that it calls them Yauna that is Ionians that is Greeks. Apparently Persians knew that Macedonians were always Greeks. The list of 478 BC has no Yauna Takabara any more. At that time Persians left Macedonia for well.
So Persians believed Macedonians to be Greeks. Actually, all non Greek peoples who met Macedonians, called them as Greeks: Jews, Romans, …
You may want to read this:
http://www.livius.org/y/yauna/yauna.html
Istor
Macedonia, Greece