The history of Thessaly covers the history of the region of Thessaly in north-central Greece from antiquity to the present day. Topography Thessaly is characterized by the large Thessalian plain, formed by the Pineios River, which is surrounded by mountains, most notably the Pindus mountain range to the west, which separates Thessaly from Epirus. Only two passes, the Porta pass and, in the summer, the pass of Metsovo, connect the two regions. From the south, the narrow coastal pass of Thermopylae connects Thessaly with southern Greece. In the north Thessaly borders on Macedonia, either through the coast or the pass of Servia towards Thessalonica, or in the northwest towards western Macedonia. Antiquity The first evidence of human habitation in Thessaly dates to the late Paleolithic, but in the early Neolithic this expanded rapidly. Over 400 archaeological sites dating to the period are known, including fortified ones. The most notable of these is at Sesklo. During the Mycenaean period, the main settlement was at Iolcos, as attested in the later legends of Jason and the Argonauts. Archaic period A distinct Thessalian tribal identity and culture first began to form from the 9th century BC on as a mixture of the local population and immigrants from Epirus, first in the region of the Pelasgiotis, with Pherae as its main centre. From there they quickly expanded inland to the plain of the Pineios and towards the Malian Gulf. The Thessalians spoke a distinct form of Aeolic Greek. In the late 7th century BC, the Thessalians conquered the so-called perioikoi. In this process the Thessalians captured Anthela and came to control the local amphictyony. By assuming the former share of the perioikoi in the Delphic Amphictyony, the Thessalians also came to play a leading role in the latter, providing 14 of the 24 hieromnemones and presiding over the Pythian Games. As a result of the First Sacred War (595–585 BC), the Thessalians briefly extended their sway over Phocis as well, but the Boeotians drove them back after the battles of Hyampolis and Ceressus in the mid-6th century. In the second half of the 7th century, Thessaly became the home of large aristocratic families, controlling huge tracts of land and working them with serfs (penestae), which became a characteristic of Thessaly. The most important were the Aleuadae of Larissa, the Echecratidae of Pharsalus, and the Scopadae of Crannon. Their clan chiefs were often called basileis