History of the Peloponnesian War

He also invited many of the Highland Thracians, who are independent, and armed with swords; they are called the Dii, and are mostly inhabitants [of the valleys] of Haemus: some of these he engaged as mercenaries, while others followed him as volunteers.

Moreover, he summoned the Agrianians and Laeaemans and all the other Paeonian tribes that acknowledged his sway. And these were the last people in his dominion, for at the Graaeans and Laeaeans, both of them Paeonian tribes, and at the river Strymon, which flows from Mount Scomius through their country, his empire terminated on the side of the Paeonians, who from this point were independent.

On the side of the Triballi, who were also independent, the border tribes were the Treres and Tilataeans, who live to the north of Mount Scombrus, and stretch towards the west as far as the river Oscius. This river flows from the same mountain as the Nestus and the Hebrus, an uninhabited and extensive range, joining on to Rhodope.

The extent then of the Odrysian dominion, taking the line of its sea-coast, was from the city of Abdera to the Euxine, up to the mouth of the Danube. This tract is by the shortest way a voyage of four days and nights for a merchant-vessel, supposing the wind to be always steady astern. By land, taking the shortest way from Abdera to the [mouth of] the Danube, a quick traveller performs the journey in eleven days.