Macedonia or Macedon was an ancient Greek kingdom. Centered in the northeastern part of the Greek peninsula, the kingdom was bordered by Epirus to the west, Paeonia to the north, the region of Thrace to the east and Thessaly to the south.

The rise of Macedon, from a small kingdom at the periphery of Classical Greek affairs, to one which came to dominate the entire Hellenic world, occurred under the reign of Philip II. For a brief period, after the conquests of Alexander the Great, it became the most powerful state in the world, controlling a territory that included the former Persian empire, stretching as far as the Indus River; at that time it inaugurated the Hellenistic period of Ancient Greek civilization.

Source: http://en.wikipedia.org/wiki/Macedonia_%28ancient_kingdom%29