Around 1000 B.C, there was a westward expansion of the ancient Greeks. In this period, the Greeks colonized big areas in Southern Italy. One of these colonies was named Poseidonia and was situated in the area that would later be called Magna Graecia by the Romans. The colony of Poseidonia was founded in the sixth century B.C. by colonists from Sybaris, which itself was a colony that was founded by colonists from the ancient Greek city Achaia in 720 B.C. The colony of Poseidonia had been transformed to a Roman colony during the rise of the Roman Empire around 300 B.C. However, to what extend did the colony really became 'Roman', and how 'Greek' was the first phase of the colony?
 The colony of Poseidonia was, as already mentioned, founded by colonist from Sybaris. This colony was founded 120 years before Poseidonia and it is therefore questionable to what extend Poseidonia was a 'Greek' city. One might suggest that after a considerable amount of time, these colonists might have seen themselves more as 'Italic people' than as 'Greeks'.  According to Skele, there have been found multiple traces of indigenous people living in the colony of Poseidonia during the 'Greek' period.1 It is therefore likely that we cannot regard the colony of Poseidonia as a purely 'Greek' city.
In 273 B.C, the colony of Poseidonia became a Roman colony known as Paestum. The Romans changed a lot in the city plan during their reign. However, can Paestum therefore be seen as a purely 'Roman' city? For example, the older temples stayed in use during the Roman times. This might seem strange, but the Romans were very tolerant in accepting other gods in their religion. According to Bradley, the indigenous habitants of Paestum continued living in Paestum after the city was taken by the Romans and took part in the government.2 Paestum therefore, has never been a purely 'Roman' city.
1 Skele 2002, 29.
2 Bradley 2006, 172-173.