No trace of their original language has been preserved, but Herodotus describes them as related to the tribes of Thracian extraction like the Phrygians and Armenians, whose languages may form part of the Paleo-Balkan group (although this is not certain and the theory is not universally accepted). Later the Greeks established on the coast the colonies of Cius (modern Gemlik); Chalcedon (modern Kadıköy), at the entrance of the Bosporus, nearly opposite Byzantium (modern Istanbul) and Heraclea Pontica (modern Karadeniz Ereğli), on the Euxine, about 120 miles (190 km) east of the Bosporus. The Bithynians were incorporated by king Croesus within the Lydian monarchy, with which they fell under the dominion of Persia (546 BC), and were included in the satrapy of Phrygia, which comprised all the countries up to the Hellespont and Bosporus. Even before the conquest by Alexander the Bithynians appear to have asserted their independence, and successfully maintained it under two native princes, Bas and Zipoites, the latter of whom assumed the title of king ("basileus") in 297 BC. His son and successor, Nicomedes I, founded Nicomedia, which soon rose to great prosperity, and during his long reign ( BC), as well as those of his successors, Prusias I, Prusias II and Nicomedes II (14991 BC), the kingdom of Bithynia had a considerable standing and influence among the minor monarchies of Anatolia. But the last king, Nicomedes IV, was unable to maintain himself in power against Mithridates VI of Pontus. After being restored to his throne by the Roman Senate, he bequeathed his kingdom through his will to the Roman republic (74 BC). The coinage of these kings show their regal portraits, which tend to be engraved in an extremely accomplished Hellenistic style. As a Roman province, the boundaries of Bithynia changed frequently. During this period, Bithynia was commonly united for administrative purposes with the province of Pontus. This was the situation at the time of Emperor Trajan, when Pliny the Younger was appointed governor of the combined provinces (109/110111/112), a circumstance which has provided historians with valuable information concerning the Roman provincial administration at that time. Under the Byzantine Empire, Bithynia was again divided into two provinces, separated by the Sangarius.