At first, he acted as regent and tutor for Alexander's infant son Antiochus VI Dionysus, but after the death of his charge in 142/141 BC, Diodotus declared himself king.

Other rebels had claimed the throne, such as Molon and Timarchus, but they never succeeded in bringing the whole realm under their control and both were defeated within a year of declaring themselves kings.

In 145 BC, when Alexander's father-in-law Ptolemy VI of Egypt switched his support to Demetrius II and invaded Syria, Diodotus and a man called Hierax were in command of the city of Antioch.

[7] He probably considered himself to be in danger, and he fled to an Arab ruler called Zabdiel or Imalkue, who had been entrusted with the care of Alexander Balas's young son.

[16] At the same time Diodotus made diplomatic overtures to the Jews under Jonathan Apphus in order to have them join with him against Demetrius, giving him honours and appointing his brother Simon Thassi as general.

Josephus justifies this by claiming that Demetrius had persecuted the Jews and that the memory of Alexander Balas encouraged them to support his son Antiochus VI.

The Jewish sources claim that the boldness of the Jonathan's attacks on Demetrius' supporters led Diodotus to fear his power and begin to plot against him.

[18][19] Simon quickly became a close ally of Demetrius II, who granted extensive freedoms to him - later seen as the moment when the Hasmonean Jewish state achieved full independence.

[22] In late 142 or early 141 BC, Antiochus VI Dionysus died, supposedly during a medical operation; most ancient sources accuse Diodotus of having had the young king murdered.

Tryphe was sometimes a negative attribute, implying softness, but could also be a positive virtue, advertising the ruler's wealth and ability to reward his subjects.

Edwyn Bevan argued that this epithet was intended to recall the Macedonian kings Philip II and Alexander the Great, who had held the title of Strategos Autokrator as elected leaders of the Greek forces against Persia.

[24] Boris Chrubasik argues that Tryphon took the epithet in imitation of the Parthian rulers and to emphasise his independence from his predecessors (the term Autokrator literally means 'ruling (by) himself').

His coins depicts him in a mature guise, with a rather fat face and long flowing hair - emphasising the luxuriousness implied by the name Trypon.

Numismatic evidence shows that many coastal cities remained loyal to Tryphon, but that Sidon and Tyre immediately attached themselves to Antiochus' cause.