Mithridates VI had quelled an uprising in the region of Colchis in 83 BCE and had given Colchis to his son Mithridates, who was soon executed being suspected in having plotted against his father.

During the Third Mithridatic War, Mithridates has made another son, Machares, king of Colchis, where Mithridates has regrouped.

At Pompey's approach, Mithridates strategically withdraws his forces.

Tigranes the Great refuses him refuge, so he makes his way to his own dominions in the Cimmerian Bosporus.

Pompey secures a treaty with Tigranes, and in 65 BCE sets out in pursuit of Mithridates, but meets resistance from the Caucasian Iberians and Albanians.

He advances to Phasis in Colchis and liaises with his legate Servilius, admiral of his Euxine fleet, before decisively defeating Mithridates.

Pompey now retraces his steps, …

…winters at Pontus, and makes it into a Roman province.

…Rome seizes Ptolemaic-ruled Cyprus.

Catiline, on returning home in 66 BCE, had presented himself as a candidate for the consular elections but a delegation from Africa appealing to the Senate, indicting him for abuses, had prevented this as the incumbent consul, Lucius Volcatius Tullus, disallowed the candidacy.

The consuls-designate, Publius Autronius Paetus and Publius Cornelius Sulla, had been prevented from entering office because of ambitus, electoral corruption, under the lex Calpurnia.

Thus, the two other leading candidates, Lucius Manlius Torquatus and Lucius Aurelius Cotta, had been elected in a second election and were to enter office on January 1, 65 BCE.

Supposedly, Catiline, incensed because he was not allowed to stand for the consulship, had conspired with Gnaeus Calpurnius Piso and the former consuls-designate to slaughter many of the senators and the new consuls the day they assumed office.

They would then name themselves the consuls for 65 BCE and would then have sent Piso to organize the provinces in Spain.

Alternatively, Suetonius claims that Julius Caesar and Marcus Licinius Crassus directed the conspiracy, but he fails to mention Catiline's involvement.

Crassus is accused of planning to become dictator instead of assuming the consulship, and of intending to name Caesar magister equitum.

Catiline in 65 BCE is finally brought to trial where he receives the support of many distinguished men, including many consulars.

Even one of the consuls for 65 BCE, Lucius Manlius Torquatus, demonstrates his support for Catiline.

Cicero also contemplates defending Catiline in court.

Catiline is acquitted, but only—as suggested to the author of Commentariolum Petitionis, possibly Cicero's brother, Quintus Cicero—by the fact that: "he left the court as poor as some of his judges had been before the trial, implying that he bribed his judges. (Commentariolum Petitionis, 3)

Pompey, whose military exploits have amassed to him great power and wealth, encounters strong opposition within the senate, led by Cato the Younger, Lucullus and—for a while—Crassus.

Crassus, as censor in 65, proposes citizenship for the Transpadane Gauls and annexation of Egypt but is blocked by Cicero and others.

Caesar, as aedile in 65, further advertises his Marian connections by organizing the restoration of Marius' battle trophies on the Capitoline Hill.

He attains great popularity—and goes deeply into debt—by financing spectacular games.

Caesar also probably cooperates with Crassus in his attempt to annex Egypt.

Philip II, son of the Seleucid king Philip I Philadelphus, briefly reigns over parts of Syria in the 60s BCE, as a client king under Pompey.

He competes with his second cousin Antiochus XIII Asiaticus for the favors of the great Roman general, but Pompey will have none of them.

In 64 BCE, Pompey marches into Syria and has Antiochus XIII Asiaticus deposed and killed by a Syrian chieftain, Sampsiceramus I. Antiochus' death is traditionally said to have ended the Seleucid dynasty, but he is survived by Philip II Philoromaeus for a short time.

No coins of Philip II are known, which is unusual for Seleucid rulers (the ephemeral Seleucus V Philometor is the only other king for which this is the case).

This may indicate that Philip did not rule in any of the mint cities.

Pompey now reconstitutes Syria, too, as a Roman province.

The Romans occupy Damascus in 64 BCE.

Although Rome will eventually permit the Nabataean kingdom to retain control of the city, it will subsequently be incorporated it into the league of ten cities known as the Decapolis because it is considered such an important center of Greco-Roman culture.

Sampsiceramus I is confirmed in power and his family is left to rule the region surrounding Emesa under Roman suzerainty following the death of Antiochus XIII,

Client rulers like Sampsiceramus I can police routes and preserve the integrity of Rome without cost to Roman manpower or to the Roman treasury; they are probably paid for the privilege.

Emesa is added to the domains of Sampsiceramus I, but the first Emesani capital is Arethusa, a city north of Emesa, along the Orontes River.

The kingdom of Sampsiceramus I is the first of Rome’s client kingdoms on the desert’s fringes.

The kingdom’s boundaries extend from the Beqaa Valley in the west to the border of Palmyra in the east, from Yabrud in the south to Arethusa in the north and Heliopolis.

Galatia, in the settlement of 64 BCE, becomes a client-state of the Roman empire, the old constitution disappears, and three chiefs (wrongly styled "tetrarchs") are appointed, one for each of the region's Gaulish tribes.

But this arrangement soon gives way before the ambition of one of these chiefs, Deiotarus, the contemporary of Cicero and Julius Caesar, who makes himself master of the other two chiefdoms and is finally recognized by the Romans as 'king' of Galatia.

The two Hasmonean brothers, whose worldliness has alienated most of their subjects, have waged a brutal struggle in the kingdom of Judah, in 64 BCE finally appeal to Pompey to be their arbiter.

Pompey, who is reorganizing the lands of the newly conquered Seleucid kingdom, now has an excuse to intervene in Judea.

Pompey attempts unsuccessfully to arbitrate between the brothers.

Cato the Younger becomes quaestor in, probably, 64.

Catiline is brought to trial later in the year, but this time it is for his role in the Sullan proscriptions.

At Cato's insistence, all men who had profited during the proscriptions are brought to trial.

Catiline. for his involvement, is accused of killing his former brother-in-law Marcus Marius Gratidianus, carrying this man’s severed head through the streets of Rome, then having Sulla add him to the proscription to make it legal.

Other allegations claimed that he murdered several other notable men.

Despite these charges, Catiline is acquitted again, though some surmise that it was through the influence of Caesar who presides over the court.

Caesar probably continues to cooperate with Crassus in his support of Catiline for the consulship in 64, and again in 63.

Catliline and Cicero, meanwhile, continue to vie for the post of consul.

During this year, Catiline is officially accepted as a candidate in the consular election for 63 BCE, and runs together with Gaius Antonius Hybrida.

Catiline is nevertheless defeated by Cicero and Antonius Hybrida in the consular election, largely because the Roman aristocracy fears Catiline and his economic plan.

The Optimates are particularly repulsed because he has promoted the plight of the urban plebs along with his economic policy of tabulae novae, the universal cancellation of debts.