By its geographic position Macedonia forms the connecting link between the Balkans and the Greek peninsula.
Four important routes converge on the Macedonian plain:
In climate Macedonia is intermediate between Europe and the Mediterranean.
The original Macedonia was Pieria and Mt.Olympus, and from there the Macedonians acquired the coastal plain of the Thermaic Gulf, which has been formed by the rivers Haliacmon, Lydias, and Axius.
These rivers, draining the wide plateaux of Upper Macedonia cut the mountain-ring of the Macedonian plain at Beroea, Edessa, and the defile of Demir Kapu.
Of the cantons of Upper Macedonia
The Macedonian plain comprised
Upper Macedonia is girt by high mountain-ranges traversed mainly by three important routes mentioned above; when united, it had strong natural defences.
The Macedonian plain is vulnerable from the sea and from Mygdonia, but the defiles leading into Upper Macedonia are easily defensible.
The natural products were horses, cattle, sheep, crops, wine, fruit, iron, gold, silver, and timber, the last two being exported in antiquity.
Oxford Classical Dictionary, 3rd ed. (1996), p.904