The fourth century BC was a period of change in Greek culture. In the greater part of the era, life in the city states, or poleis, continued as it had been established for centuries. The important change came when the Macedonian king, Alexander the Great (336—323 BC), conquered the Persian Empire. This was followed by the emergence of empires ruled by Greek kings in a vast territory that stretched from Hellas to the area of today’s Afghanistan. The Greek way of life and a Hellenistic education became universal in the culture of the period. The sculptural tradition of the century was defined by artists like Praxiteles and Lysippos, both of whom were considered as one of the greatest sculptors by ancient art historians. Their statues did not survive — save for a few doubtful pieces —, but we can still appreciate them because sculptors living in the later centuries of antiquity regarded them as models, and used them as inspirations when creating their own works of art. At times they aimed to make exact replicas, at times they reinterpreted them freely to design their own statues.