What political alliance allowed Julius Caesar to have an extended period of time to dominate Gaul and Illyria?

Answer 1

The alliance was the First Triumvirate, the three-men informal political alliance between Julius Caesar, Pompey the Great and Marcus Licinius Crassus. Caesar was given the governorships of Cisalpine Gaul (in northern Italy), Illyria and Transalpine Gaul (in southern France). He was given these governorships for five years and then they were extended for another five years. During this period Caesar conquered the rest of Gaul.

Julius Caesar did not subjugate Illyria. He hardly got involved in Illyria because he was too busy with his Gallic Wars. He conducted only one campaign there because of some wrong doing by one of the tribes there and then returned to Gaul.

Illyria was subjugated by Augustus after the death of Caesar (44 BC), in the campaigns he conducted there in 35- 33 BC. The area became a proper Roman province intended as an administrative unit of the empire (during the time of Julius Caesar Illyria was a province in the sense of a military jurisdiction; It was not part of the Roman Empire yet) in 27 BC. It became the province of Illyricum (the Latin name for the area)

Answer 2

Julius Caesar benefited from his alliance with Pompey and Crassus. Most importantly, this alliance gave Caesar time to subjugate Gaul and Illyria.