the Greek cities of Kallatis and Dionysupolis in the area corresponding to the present-day Dobruja both being surrounded by Scythian territory; and, in 496 or 495 BC, the Scythians raided the Thracian territories far to the south of the Danube till the Thracian Chersonese on the Hellespont, as an attempt to secure themselves from Persian encroachment. The emergence of the Thracian Odrysian kingdom during the 5th century BC soon blocked the Scythian advances in Thrace, and the Scythians established friendly contacts with the Odrysians, with the Danube river being set as the common border between the two kingdoms, and a daughter of the Odrysian founder king Tērēs I marrying the Scythian king Ariapeithes; these friendly relations also saw the Scythians and Thracians adopting aspects of each other's art and lifestyles. Names of kings who ruled over the Scythians the 5th century BC are known, although it is unknown whether these kings were ruling only the western regions of Scythia located between the Danube and Pontic Olbia or over all the Scythians: Ariapeithes Scyles, the son of Ariapeithes by a Greek woman from Histria Octamasadas, the son of Ariapeithes by the daughter of the Thracian Odrysian king Teres I. Octamasadas deposed Scyles and replaced him on the throne In the north and north-west, Scythian expansionism manifested itself through the destruction of the fortified settlements of the forest steppe and the subjugation of its population. In the south, the Scythians tried to impose their rule over the Greek colonies on the northern shores of the Black Sea: the Greek settlement of at Taganrog on the lower reaches of the Don river river, which was the only Greek colony in that area, had already been destroyed by the Scythians between 550 and 525 BC, and, owing to the Scythians' necessity to continue commerce with the Greeks, was replaced by a Scythian settlement at which became the principal trade station between the Greeks and the Scythians in this region. Although the relations between the Scythians and the Greek cities of the northern Pontic region had until then been largely peaceful and the cities previously had no defensive walls and possessed unfortified rural settlements in the area, new hostile relations developed between these two parties, and during the 490s BC fortifications were built in many Pontic Greek cities, whose were abandoned or destroyed, while burials of men killed by Scythian-type arrowheads appeared in their nekropoleis.