Eurasia has underwent much turmoil since Noah's sons stepped off the Ark and spread across the globe. On the same peninsula as the Greeks, biblical Macedonia was between Greece and Thrace. More than likely, seafaring Phoenicians probably landed and settled there. The region of Macedonia then appears to have also included the country of Albania in addition to today's Macedonia. Alexander the Great was reportedly from Macedon and neutralized the Persian threat.

As the map below shows, Philippi & Thessalonica were towns in that region.
So, clearly the books of Philippians, 1 Thessalonians & 2 Thessalonians were correspondance with the churches in those towns.