The earlier part of the Zhou dynasty is called the Western Zhou. This was the empire father and son Wen and Wu. The center of the empire then was the Yellow River Valley and succession was based on kinship. While the empire expanded eastward, the center shifted in that direction as well and the Eastern Zhou was born. The new capital was moved in an area near what is now Luoyang. This was a time when the leaders were chosen based on an autocracy. This period also saw the beginning of taxation and forced labor. The empire had slowly fragmented into smaller kingdoms until in 481 BC, it was appropriately termed as an empire of Warring states. The once great empire was divided into three, the Wei, Han and Zhao. This was a time of feudalism and when a uniform currency was established to facilitate trade with farther regions.