The tribes of the Thracians, through whose districts the expedition marched, submitted without opposition. These were the inhabitants of the region of Salmydessus; the Odrysae in the valley of the Artiscus (_i.e._ the Teke deresi or Nessowa), the Skyrmiads and Nipsaeans, who dwelt near Apollonia, the Greek city on this coast (a colony of Miletus, now Sizepoli), and Mesembria, now Misivri (a colony of the Greeks, planted soon after the other).[266] It was not till the Persians had passed the heights of the Balkan that they found resistance. Between this range and the Danube were the Getae, called by Herodotus the most brave and just of all the Thracians. They offered an obstinate resistance, but were nevertheless at once crushed by overpowering numbers.[267] Meanwhile the fleet had advanced two days' voyage up the river from the mouth, and placed the bridge there, _i.e._ at the place where the river becomes one stream. By this bridge the Greek army, to use the expression of Herodotus, passed "over the greatest river which we know." Strabo says that the bridge was placed over the lower part of the southern, and largest, of the mouths of the Danube; which was called the sacred mouth. On the further shore began the land of the Scoloti. When the army had crossed the Danube, Darius, as Herodotus relates, wished to destroy the bridge and employ the crews in his army. But on the advice of Coes of Lesbos, who pointed out that he must leave the way open for his return, Darius abandoned his purpose; he then summoned the princes of Ionia, and gave them a thong with 60 knots, bidding them untie a knot each day. If the army did not return to the bridge in these 60 days they were to go home.[268]