Between 450 and 400 BC, Kerkinitis was paying tribute to the Scythians. The Scythians were eventually able to successfully impose their rule over the Greek colonies in the north-western Pontic shores and in western Crimea, including Niconium, Tyras, Pontic Olbia, and Kerkinitis. The hold of the Scythians over the western part of the Pontic region thus became firmer during the 5th century BC, with the Scythian king Scyles having a residence in the Greek city of Pontic Olbia which he would visit each year, while the city itself experienced a significant influx of Scythian inhabitants during this period, and the presence of coins of Scyles issued at Niconium in the Dnister valley attesting of his control over this latter city. This, in turn, allowed the Scythians to participate in indirect relations with the city of Athens in Greece proper, which had established contacts in Crimea. The destruction of the Greek cities' and rural settlements however also meant that they lost their grain-producing hinterlands, with the result being that the Scythians instituted an economic policy under their control whereby the sedentary peoples of the forest steppe to their north became the primary producers of grain, which was then transported through the Southern Buh and Dnipro rivers to the Greek cities to their south such as Tyras, Niconium and Pontic Olbia, from where the cities exported it to mainland Greece at a profit for themselves. The Scythians were less successful at conquering the Greek cities in the region of the Cimmerian Bosporus, where, although they were initially able to take over Nymphaeum, the other cities built or strengthened city walls, banded together into an alliance under the leadership of Panticapaeum, and successfully defended themselves, after which they united into the Bosporan Kingdom. After Scyles, coins minted in Pontic Olbia were minted in the name of Eminakos, who was either a governor of the city for Scyles's brother and successor, Octamasadas, or a successor of Octamasadas. Around the same time, there were inner conflicts within the Scythian kingdom, and a new wave of Sauromatian immigrants arrived into Scythia around , which destabilised it and ended Scythian military activity against the Greek cities of the Pontic shore. Scythian control of the Greek cities ended sometime between 425 and 400 BC, and the cities started reconstituting their , and Pontic Olbia regained control over the territory it occupied during the Archaic period and expanded it,