The empire inherited in 187 BCE by Antiochus' thirty-year-old son, Seleucus IV Philopater (“Father-loving”), though much reduced after the war with Rome (190-189), is still large, consisting of Syria (including Cilicia and Palestine), Mesopotamia, Babylonia, and nearer Iran (Media and Persia).

Pontus gradually has asserted itself among the petty Hellenistic states of Anatolia in the third and early second centuries BCE; Pharnaces, fifth king of Pontus, the son of Mithridates III, who he succeeded on the throne, succeeds in reducing Antiochus, …

…the important city of Sinope, which has been long an object of ambition to the kings of Pontus, and annexes the city in 183 as the new Pontic capital.

The Rhodians send an embassy to Rome to complain of this aggression, but without effect.

About the same time, Pharnaces becomes involved in disputes with his neighbor, Eumenes II, king of Pergamon, which leads to repeated embassies from both monarchs to Rome, as well as to partial hostilities.

The Jews under the Syrian Seleucids are treated even more liberally than they had been under the Egyptian Ptolemids, being granted a charter to govern themselves by their own constitution, namely, the Torah.

Greek influence, however, is already becoming manifest.

Some of the twenty-nine Greek cities of Palestine attain a high level of culture.

The years from 188 BCE onward are lean years for the dynasty, because the war with Rome, which had ended in a complete Roman victory, had cost it not only almost the whole of Asia Minor but also a yearly indemnity of fifteen thousand talents.

Unsurprisingly, the first account of Seleucid rule in Palestine tells of an attempt by Heliodorus, the leading minister of Seleucus IV, to deprive the Second Temple in Jerusalem of its treasure.

His failure is soon ascribed to divine protection.

The apocryphal writer Jesus ben Sirach so bitterly denounces the Hellenizers in Jerusalem that he is forced by the authorities to temper his words.

Egypt’s Hellenistic regent Cleopatra I, although a daughter of a Seleucid king, has not taken sides in Syria and remains friendly with Rome.

Mother and son govern effectively until her death in 176, when ten-year-old Ptolemy VI Philometor (Greek: Loving his Mother), beset by problems of dynastic rivalry, becomes sole ruler of Egypt, and immediately falls under the influence of two ambitious courtiers.

Perseus the eldest son and successor in 179 BCE of the recently deceased Philip V of Macedon, secures his position by arranging dynastic marriages with other Hellenistic kings, taking the daughter of Seleucus IV of Syria as his wife and giving the hand of his sister to Prusias II of Bithynia, son of Prusias I Cholus.

In addition, he uses diplomacy to extend his influence.

Financial difficulties, created in part by the heavy war indemnity exacted by Rome, have compelled Seleucus IV to pursue a policy devoid of expensive adventures.

His unambitious policy and care are also dictated by the fact that his son and heir, Demetrius, has been sent to Rome as a hostage for his father in exchange for Antiochus, the third son of Antiochus III, who has learned to admire Roman institutions and policies.

Seleucus, having heard that the temple treasury in Jerusalem is wealthy, wonders why some of the tribute is being withheld.

He sends one his chief ministers, Heliodorus, to investigate.

Heliodorus, having possibly found enough wealth to bribe elements in the Seleucid army, returns, assassinates Seleucus, and seizes the throne in 175.

As Seleucus' legitimate heir, Demetrius, is still a hostage in Rome, Antiochus, with the help of King Eumenes II of Pergamon, seizes the throne for himself, proclaiming himself co-regent for another son of Seleucus, an infant named Antiochus (whom he will murder a few years later).

He takes the throne as Antiochus IV Epiphanes (”God Manifest”).

Both economically and socially, Antiochus, a passionate philhellene who pays lip service to the political traditions of both Athens and Rome, makes efforts to strengthen his kingdom—inhabited in the main by Orientals (non-Greeks of Asia Minor and Persia)—by founding and fostering Greek cities.

Even before he had begun his reign, he had contributed to the building of the temple of Zeus in Athens and to the adornment of the theater.

He enlarges Antioch on the Orontes by adding a section to the city (named Epiphania after him).

Here he builds an aqueduct, a council hall, a marketplace, and a temple to Jupiter Capitolinus.

Abrupolis, a king of the Thracian Sapaei, and ally of the Romans, had attacked the dominions of Perseus around 179 BCE, and laid them waste as far as Amphipolis, as well as overrunning the gold mines of Mount Pangaeus.

He is eventually driven out of his holdings by Perseus, the conflict of which helps ignite the Third Macedonian War, since Rome takes issue with the ousting of an ally from his territories.

Flamininus, throughout his stewardship of Greece, has attempted to preserve Greek local autonomy, but Rome abandons this policy soon after his death in 174.

While some ancient (and modern) writers considered Abrupolis's routing by Perseus a primary cause of the Third Macedonian War, other, later Roman writers, and modern scholars, tended to look upon it as an act of self-defense, with Rome merely using it as one pretext for a quarrel with Perseus.