183 BC Pharnaces succeeded in reducing the important city of Sinope, which had been long an object of ambition to the Kings of Pontus. The Rhodians sent an embassy to Rome to complain of this aggression, but without effect. Disregarding the potential for an international incident, Pharnaces proceeded to celebrate the conquest by founding the city of Pharnaceia from two of Sinope's former colonies. He also made Sinope the new primary residence of the Pontic Kings.

SHH v4154 Pharnaces / Hermes CNG Triton XIX/2053

The articles of the Peace of Apameia (188 BC), which granted Phrygia to the Attalic king, Eumenes II Scoter of Pergamon, rankled with Pharnaces I, who also claimed rights over parts of Phrygia. A dispute ensued, which led to repeated embassies from both monarchs to Rome, as well as to partial hostilities. But in the spring of 181 BC, without waiting for the return of his ambassadors, Pharnaces I mounted an invasion of Galatia and Paphlagonia trying to enforce his claims. This resulted in conflict with Eumenes II, Prussias II of Bithynia, Ariarathes IV of Cappadocia and the Paphlagonian Morzius. Pharnaces was supported by Mithradates of Armenia  Minor  and

Seleucus IV. Roman commissioners attempted to haltthe war through arbitration, but when they decided that Pharnaces' demands were unreasonable, the fighting continued. Pharnaces' general Leocritus (Λεώκριτος) occupied Tius (Τίον) in Bithynia. In an effort to suppress the resistance of the Pontic cities Pharnaces had the Sarmatian chieftain Gatalus attack the Tauric Chersonesus, a colony of Heraclea Pontica. The conflict only came to an end 179 BC, after the exhaustion of the Pontic kings' military and financial resources forced him to withdraw. He was compelled to purchase peace with the cession of all his conquests in Galatia and Paphlagonia, with the exception of Sinope. Heavy reparations were imposed on Pontos and Armenia Minor. The peace treaty also required from Pharnaces to protect Chersonesus Taurica, Mesembria and Heraclea Pontica from Sarmatian attacks.

Pharnaces married a Seleucid Princess called Nysa, who was the child of princess Laodice IV and crown prince Antiochus. Nysa and Pharnaces were related as the parents of Nysa were his first cousins. Pharnaces married Nysa either in 172 BC or 171 BC, through the diplomatic work of the Seleucid King Demetrius I Soter.

Honorific statues and inscriptions have survived that were dedicated to Pharnaces and Nysa. Pharnaces set about to establish good relations with the citizens of Athens and the Greek island of Delos. He made a benefaction to the people of Athens. The exact nature of the benefaction is unknown; Pharnaces may have made some kind of voluntary donation to Athens, possibly soon after 183 BC. A lengthy honorific inscription from the Athenians on Delos honours Pharnaces and Nysa. They received a crown of gold from them and bronze statues of themselves were set up on Delos. Their lengthy Athenian honorific inscription is dated in the Archonship of the Athenian Tychandrus or Tychander which is now generally accepted as 160 BC or 159 BC.

Nysa bore Pharnaces two children: a son called Mithradates V of Pontus and a daughter called Nysa of Cappadocia, who is also known as Laodice.

References

Hoover Oliver D.   2012
The Handbook of Greek Coinage Series, Volume 7 - Coins of Northern and Central Anatolia
CNG Lancaster/London, 2012, p. 105

Ροδάκης Περικλής   2003
Ιστορία του Πόντου, Τόμος 1ος,  Γόρδιος, Αθήνα, 2003, Σελ.133

Smith William   1846
Dictionary of Greek and Roman Biography & Mythology Vol. II
Taylor & Walton, London, 1846

Wikipedia - Pharnaces I of Pontus
https://en.wikipedia.org/wiki/Pharnaces_I_of_Pontus Χριστόπουλος Γεώργιος (Διευθυντής Εκδόσεως)  1973

Ιστορία του Ελληνικού Εθνους
Τόμος E', Εκδοτική Αθηνών, 1974, Σελ. 133-134