Ancient civilizations were diverse culturally and institutionally, so there was imbalanced evolution in social format. By the fifth century CE, China had been feudal for several centuries, while other major agrarian civilizations in Asia, Africa, and Europe were still in the midst of transforming from slave societies to feudal ones, and the civilizations in the Americas were still in their early slave-society periods. In general, for a period of over 600 years, Asia was at the forefront of global development.