The Roman Empire was well-established, so what are you talking about? The first conquest was of nearby Ostia (now a tourist attraction, Ostia Antica). Other neighboring settlements got gobbled up during the second half of the last millennium BC. The so-called Roman Republic was a hereditary oligarchy, where a handful of families owned and/or ran everything, and it had an empire that included most of Italy. The title Imper Iter (emperor) was bestowed many a time before Julius Caesar (including upon his colleague and rival, Pompey), but the count is generally begun with Octavian/Augustus, who was the first permanent chief executive, an evolved necessity; if anything the Roman Empire was far more egalitarian and representative than the so-called republic ever was or was intended to be.
The Republic was expanding its sphere of influence for centuries, but there was no empire until founded by Augustus in 27 BC.