Within 100 years of the period of settlement of Greek cities in Sicily, the cities had prospered enough to begin consolidating into a structure of city-states. In Agrigento, Phalaris seized the title of Tyrant, c. 570 BC. He soon added Himera to his domain, then extended his rule over substantially all of Greek Sicily, before being deposed and slain in a torture device that he had introduced himself.

In the following century Gelon managed a more lasting rise to power. Upon the death of Hippocrates, Tyrant of Gela, in 491 BC, Gelon, his commander of cavalry, seized the throne. Six years later he allied with the Gamori, who had been deposed as oligarchic rulers of Syracuse. He quickly added Syracuse to his domain and transferred the center of his activities to that city. Under his leadership Syracuse became the richest and most powerful of the Greek cities of Sicily, but a powerful challenge arose quickly with invasion of Sicily by Carthage.