The word that exactly defines colony is apoikia, which means far from home, is a city-state. When they founded a colony, many people from the metropolis (mother city) went to live in the colony.
Found a apoikia It is not making a migration, it is extending the territory to enrich itself with new lands and new treasures. There were the klerukis that were farmland and the emporium that was for commercial exchange, all different in structure.
Most of the time the colonies were founded to establish and affirm trade with foreign peoples, to increase the land and wealth of the metropolis.
Magna Graecia was the name that the Romans gave to the former Greek colonies of southern Italy and Sicily.
After the war between Athens, Turios and the hostile Tarentum, they moved Siris near the mouth of the Aciris river, they called that new colony Heraclea, which was a colony of Taranto. Many of the inhabitants of the old Siris came to live in the new Heracleia. It is believed to have been founded around 432 BC
Livy later names it as a colony of Tarento.
Heraclea was a greek colony 5 km from the coast of the Gulf of Taranto, in Lucania, between the Aciris and Sinis rivers.
Heracleia It was founded in the area where the Ionic colony of Siris had been, it was one of the colonies that was later founded in the area.
Siris continued to be inhabited but became dependent on Heraclea.