Demetrius II, attempting to halt the rapid disintegration of the Seleucid kingdom, drives back a Parthian invasion in 140; but the tide of the Syrian-Parthian War turns against Demetrius and his Syrian troops in Parthia.

The Parthians decisively defeat Demetrius in 139 BCE, taking him captive but allowing him to maintain a royal household.

Demetrius's queen Cleopatra Thea meanwhile is regent; but the usurper Trypho has gained strength in the south and threatens to seize full power.

Antiochus, the twenty-year-old brother of Demetrius (and the son of Demetrius I) has spent his youth in the Greek islands.

The energetic prince now arrives in Syria, marries Cleopatra Thea, and takes the throne as Antiochus VII Euergetes, or Sidetes. (His nickname comes either from the city of Side, in Pamphylia, where he had possibly been brought up, or from the city of Sidon.)

A passage in the Bible (I Maccabees 14:1-14) suggests that he had first assured himself of the neutrality of possible opponents, such as Judah.

Simon, on his own initiative, has brought peace and security to Jerusalem, and formalized what Judas had begun, the establishment of a theocracy, something not found in any biblical text.

He soon becomes independent of the Seleucids as high priest, ruler, and ethnarch of Judaea; the offices are hereditary, and Simon thus becomes the first of the Hasmonean dynasty.

Judaean ambassadors to Rome In 139 BCE return with a senatorial decree recognizing the independence of the Jewish state and commending the Jewish people to the friendship of all kingdoms in the East within the Roman sphere of influence.

Simon thus acquires the status of a recognized secular ruler; the year of his assumption of rule is regarded as the first of a new era, and official documents are dated in his name and by his regnal year.

Scipio Aemilianus Africanus Minor, the Roman hero of the Third Punic War, is posted as an ambassador to eastern kingdoms in 140—139 BCE.

Meanwhile, Rome’s praetor (civil administrator) in 139 charges the Jews of the city with attempting to contaminate Roman morals with their religion, presumably an allusion to proselytism.

Rome's campaigns in Spain against the belligerent Iberians have been protracted, unprofitable, and costly in Roman casualties.

Following the defeat of Quintus Fabius Maximus Aemilianus by Lusitanian leader Viriathus in 142 BCE, Rome had sent one of its best generals, Q. Fabius Maximus Servilianus, to Iberia.

Near Sierra Morena, the Romans fall into a Lusitanian ambush.

Viriathus does not harm the Romans and lets the soldiers and Servilianus go.

Servilianus makes a peace term that recognizes the Lusitanian rule over the land they have conquered.

This agreement is ratified by the Roman Senate and Viriathus is declared "amicus populi Romani", an ally of the Roman people.

However, the peace brought by the treaty displeases Quintus Servilius Caepio, who had gotten himself appointed successor of his brother, Q. Fabius Maximus Servilianus, in the command of the army and administration of affairs in Iberia.

In his reports to the Roman Senate, he sustains that the treaty is in the highest degree dishonorable to Rome. (Livy seemed to have a different opinion, as he said it was a stain in Servilianus' military career but comments that the treaty was aequis, fair.)

The senate authorizes Q. Servilius Caepio, on his request, to distress Viriathus as long as it is done secretly.

Parthian activity had forced Demetrius II to take action in 139 BCE.

Marching against Mithridates I, king of Parthia, he was initially successful, but is defeated in the Iranian mountains and taken prisoner the following year.

This effectively ends Seleucid claims to any land east of the Euphrates river.

The Babylonian province of the Seleucid empire becomes Parthian, but …

…in Syria the dynasty's grip is reassured under Antiochus VII Sidetes, the younger brother of Demetrius, who also marries Cleopatra Thea.

Antiochus, having put Trypho to flight and ended his career, ...

…delivers an ultimatum in 138 BCE to the Jews to acknowledge him as overlord.

When they refuse, he sends an army against them, led by his general, Cendebeus.