The Hellenistic period is the period of ancient Greek and eastern Mediterranean history between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire as signified by the Battle of Actium in 31 BC and the subsequent conquest of Ptolemaic Egypt the following year. At this time, Greek cultural influence and power was at its peak in Europe, Africa and Asia, experiencing prosperity and progress in the arts, exploration, literature, theatre, architecture, music, mathematics, philosophy, and science. It is often considered a period of transition, sometimes even of decadence or degeneration, compared to the brilliance of the Greek Classical era.After Alexander the Great's ventures in the Persian Empire, Hellenistic kingdoms were established throughout south-west Asia (Seleucid Empire, Kingdom of Pergamon) and north-east Africa (Ptolemaic Kingdom). This resulted in the export of Greek culture and language to these new realms, and moreover Greek colonists themselves. Equally, however, these new kingdoms were influenced by the indigenous cultures, adopting local practices where beneficial, necessary, or convenient. Hellenistic culture thus represents a fusion of the Ancient Greek world with that of the Near East, Middle East, and Southwest Asia, and a departure from earlier Greek attitudes towards "barbarian" cultures. The Hellenistic period was characterized by a new wave of Greek colonization (as distinguished from that occurring in the 8th–6th centuries BC) which established Greek cities and kingdoms in Asia and Africa. Those new cities were composed of Greek colonists who came from different parts of the Greek world, and not, as before, from a specific "mother city". The main cultural centers expanded from mainland Greece to Pergamon, Rhodes, and new Greek colonies such as Seleucia, Antioch and Alexandria. This mixture of Greek-speakers gave birth to a common Attic-based dialect, known as Koine Greek, which became the lingua franca through the Hellenistic world. Scholar and historians are divided as to what event signals the end of the Hellenistic era. The Hellenistic period may be seen to end either with the final conquest of the Greek heartlands by Rome in 146 BC following the Achean War, with the final defeat of the Ptolemaic Kingdom at the Battle of Actium in 31 BC, or even the move by Roman emperor Constantine the Great of the capital of the Roman Empire to Constantinople in 330 AD.