DiodotusTryphon was king of the Seleucid kingdom of Syria.
As a general of the army, he promoted the claims of the infant son of Alexander Balas, but then in 142 deposed and killed the child and himself seized power in Palestine where Demetrius II was unpopular for his oppressive treatment of the Jews.
However, internal strife led in 143 to the establishment of Hasmonean rule, and in 138 Diodotus was attacked and defeated in Antioch by Antiochus VII of Side.
As Demetrius II did not keep his promise, Jonathan thought it better to support the new king when DiodotusTryphon and Antiochus VI seized the capital, especially as the latter confirmed all his rights and appointed his brother Simeon strategos of the seacoast, from the "Ladder of Tyre" to the frontier of Egypt.
DiodotusTryphon went with an army to Judea and invited Jonathan to Scythopolis for a friendly conference, and persuaded him to dismiss his army of 40,000 men, promising to give him Ptolemais and other fortresses.
Although Simeon did not trust DiodotusTryphon, he complied with the request in order that he might not be accused of the death of his brother.