For the Levant and Mesopotamia, it meant coming under the control of Seleucus I Nicator and the Seleucid Empire. The Hellenistic period was characterized by a new wave of Greek colonization.[5] Ethnic Greek colonists came from all parts of the Greek world, not, as before, from a specific "mother city".[6] The main centers of this new cultural expansion of Hellenism in the Levant were cities like Antioch, and the other cities of the Tetrapolis Seleukis. The mixture of Greek-speakers gave birth to a common Attic-based dialect, known as Koine Greek, which became the lingua franca throughout the Hellenistic world.