 As the Greek and Phoenician communities grew more populous and more powerful, the Sicels and Sicanians were pushed further into the centre of the island.By the 3rd century BC, Syracuse was the most populous Greek city in the world.Sicilian politics was intertwined with politics in Greece itself, leading Athens, for example, to mount the disastrous Sicilian Expedition in 415 BC during the Peloponnesian War.