The Hellenistic period or Hellenistic era of history is the period which followed the conquests and death of Alexander the Great in 323 BC. The Hellenistic period may be seen to end either with the final conquest of the Greek heartlands by Rome in 146 BC or with the final defeat of the last remaining successor-state to Alexander's empire after the Battle of Actium in 31 BCE. The Hellenistic period was characterized by a wave of colonists who established Greek cities and kingdoms in Asia and Africa.
It was so named by the historian J. G. Droysen. During this time, Greek cultural influence and power was at its zenith in Europe and Asia. It is often considered a period of transition, sometimes even of decline or decadence, between the brilliance of the Greek Classical era and the emergence of the Roman Empire.
"The Hellenistic Period" (Wikipedia) http://en.wikipedia.org/wiki/Hellenistic_period