Greece has a long history dating back to 800 BC when small city-states developed along trade routes between Asia, Africa and Europe. These city-states contributed greatly to Western civilization through their advances in philosophy, art, architecture and literature. Greece was later conquered by both the Roman Empire and the Ottoman Turks, with the latter ruling for 400 years until Greek independence was achieved in the 1830s. Today, Greece remains heavily influenced by its Byzantine and Ottoman past, with the dominant Eastern Orthodox religion and Turkish cultural influences still present. The economy continues to lag behind other European nations, relying on agriculture, tourism and shipping.