Medieval Greece refers to the period from the fall of the Western Roman Empire in the 5th century to the rise of the Ottoman Empire in the 15th century. During this time, Greece was influenced by various powers, including the Byzantine Empire, which played a significant role in preserving Greek culture and Orthodox Christianity. The region experienced significant changes, including the establishment of city-states and the spread of feudalism. The Crusades also impacted Greece, leading to the temporary occupation of parts of the country by Western European powers. This era laid the groundwork for the cultural and political developments that followed.