According to traditional historical sources, the Shang Dynasty was founded by Tang the Perfect (Cheng Tang, Chengtang) 成湯) who defeated the depraved ruler Jie 桀 of the Xia 夏 kingdom. Jie was banished to Nanchao 南巢 in the Yangtse River region. Before this event, the Shang chieftains are said to have changed their capital eight times, after the foundation of the dynasty the kings five times changed their residence. Scholars suppose that the Shang people either was an old nomadic people that once settled down but retained the custom of temporarily changing residence, or that the Shang people was forced to move their community forced by inundations or droughts. It might ... be that the Shang had to remove because stronger neighbors forced them to leave their dwellings. The second ruler, Wai Bing (Waibing) 外丙 installed Yi Yin (Yiyin) 伊尹 as his highest minister (qingshi 卿士) who served three subsequent kings but finally tried to depose King Tai Jia (Taijia) 太甲.