It's also probably worth mentioning the 1913 Treaty of Bucharest here. The treaty itself mentions Macedonia and as part of the region it refers to under the name of Macedonia, it also includes what is the territory of the Republic of Macedonia today.
To prove you wrong and to further reiterate that the territory of the Republic of Macedonia is part of Macedonia and has been referred to as such, I will refer you to the website of
Greek Ministry of Foreign AffairsLink:
http://www.mfa.gr/NR/rdonlyres/672ADA69 ... treaty.docExcerpt:
"TO THE RELATIVELY brief text of this treaty were appended three protocols concerning the frontiers of Bulgaria, which had been defeated in the Second Balkan War. The third of these protocols referred to Greece, which at the end of the War had acquired Crete1 and Kavala. The northern frontier of Greece was defined as extending from the north of Korytsa, between Monastir and Florina, to Doiran, then south of Strumitsa, Petrich and Nevrokopi, to the mouth of the Nestos (Mesta).
The Peace Treaty of Bucharest was the outcome of the conference convened after the conclusion of the Second Balkan War, on the initiative of King Carol of Roumania.2
Bulgaria lost the greater part of Macedonia, whose territory was divided between Greece and Serbia. During the conference, the Bulgarian delegates at times adopted an attitude that was seen as provocative by the other participants, given that Bulgaria had been the aggressor and was, moreover, the defeated side. There were also times, however, when they were strikingly conciliatory. This was because Bulgaria hoped that the Great Powers would revise the treaty, a hope encouraged by both Austria and Russia. France and Germany were opposed to such a revision, while Italy and Britain were prepared to accept it only if it was unanimously agreed upon. The European Powers were wary of the possibility of further unrest in the Balkans.
The delegations were headed at the conference by their respective Prime Ministers; Greece was represented by Eleftherios Venizelos, Serbia by N. Pachic, Roumania by T. Maioresco and Montenegro by S. Voukotic, whilst defeated Bulgaria was represented by Finance Minister D. Tontchev.
Through the Treaty of Bucharest, the territory of Greece doubled in size3 and its population increased by some two million, reaching 4,718,221 inhabitants.4 Although this expansion could have been considerably greater, it was significant as it included sources of wealth, providing the conditions for industrialisation and economic development. It also improved Greece’s international standing. With its special position in the network of Balkan relations and in the balance of political and military power in Europe, the modern Greek state acquired an unprecedented role."
You see that 'greater part of Macedonia that was divided between Greece and Serbia'? Well the bit that went to Serbia is today the independent Republic of Macedonia.
Yes, that's right, the Treaty of Bucharest, and your own Foreign Ministry, refer to the territory of the Republic of Macedonia, as Macedonia.