Greek culture has evolved over thousands of years, with its beginning in the Mycenaean civilization, continuing through the classical era, the Hellenistic period, the Roman and Byzantine periods and was profoundly affected by Christianity, which it in turn influenced and shaped. Ottoman Greeks had to endure through several centuries of adversity that culminated in genocide in the 20th century. The Diafotismos is credited with revitalizing Greek culture and giving birth to the synthesis of ancient and medieval elements that characterize it today.