Mithridates II (the Great) was king of Parthia from 123 to 88 BC. His name invokes the protection of Mithra. He adopted the title Epiphanes, "god manifest" and introduced new designs on his extensive coinage. Parthia reached its greatest extent during his reign. He saved the kingdom from the Saka tribes, who occupied Bactria and the east of Iran and killed two of his his predecessors in battle. Mithridates II extended the limits of the empire, according to the 3rd century Roman historian Junianus Justinus who tends to confuse him with Mithridates III, under whom Parthia received severe setbacks. He defeated King Artavasdes I of Armenia and conquered seventy valleys, making the heir to the Armenian throne, prince Tigranes, a political hostage. In 123 BC and 115 BC he received Chinese ambassadors sent by the Han emperor Wu Di to reopen the Silk Road through negotiations. His later coins show him bearded, wearing the high domed Parthian crown applied with a star. He also interfered in the wars of the dynasts of Syria. He was the first Parthian king who entered into negotiations with Rome, then represented by Lucius Cornelius Sulla, praetor of Cilicia in 92 BC.