The economic history of China covers thousands of years and the region has undergone alternating cycles of prosperity and decline. China, for the last two millennia, was one of the world's largest and most advanced economies. Economic historians usually divide China's history into three periods: the pre-imperial era before the rise of the Qin; the early imperial era from the Qin to the rise of the Song (221 BCE to 960 CE); and the late imperial era, from the Song to the fall of the Qing.