When he had arrived at Therma, Xerxes quartered his army there. Its encampment by the sea covered all the space from Therma and the Mygdonian country to the rivers Lydias and Haliacmon, which unite their waters in one stream and so make the border between the Bottiaean and the Macedonian territory. In this place the foreigners lay encamped; of the rivers just mentioned, the Cheidorus, which flows from the Crestonaean country, was the only one which could not suffice for the army's drinking but was completely drained by it.