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.

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.

The treaty between Rome and the Lusitanians is in effect for one year, during which time Servilius Caepio harasses Viriathus and keeps making pressure with his reports until he is authorized to publicly declare war.

Knowing that the Lusitanian resistance is largely due to Viriathus' leadership, Servilius Caepio bribes Audax, Ditalcus and Minurus, who had been sent by Viriathus as an embassy to establish peace.

According to Appian, these ambassadors returned to their camp and killed Viriathus while he was sleeping.

The three men have escaped by the time the Lusitanians discover the death of their leader.

Unable to avenge him they instead hold feasts, gladiator battles and a grand funeral.

Eutropius claims that when Viriathus' assassins asked Servilius Caepio for their payment he answered that "it was never pleasing to the Romans, that a general should be killed by his own soldiers.".

In another version more common in modern Portugal and Spain, "Rome does not pay traitors who kill their chief".

In any event, Servilius Caepio is refused his Triumph by the Senate and the Lusitanians keep fighting under the new leadership of one Tantalus.

Simon's sons Judas and John command the force that repels the Seleucid invasion of Judah in 137.