Complex sentence: Speculators from Italy rushed into the island and bought up large tracts of land at a low price, or became the occupiers of estates which had belonged to Sicilians of the Carthaginian party and had been forfeited to Rome after the execution or flight of their owners.
Split into simpler sentences: Speculators from Italy rushed onto the island, buying up large tracts of land at low prices, or occupied estates which had belonged to Sicilians of the Carthaginian party. These were forfeited to Rome after the execution or flight of their owners.