alexander the great conquered an area from turkey to pakistan in the 4th century bc. the roman empire would later control parts of western asia. the achaemenid, seleucid, parthian and sassanian empires were based in ancient persia. many ancient civilizations were influenced by the silk road, which connected china, india, the middle east and europe. the vedic religion and later buddhism, which began in southern asia, were an important influence on south and east asia.