The Chou conquered the Shang Dynasty about 1100 BC (the traditional date is 1122). The Chou said that the reason they were able to conquer the Shang was that Heaven was on their side. According to Chinese stories, backed up in some points by oracle bones, the first really independent king of the Chou Dynasty was King Wu. According to the stories, King Wu led a big army with chariots down the south bank of the Yellow River. In 1046 BC King Wu crossed the Yellow River and conquered the Shang Dynasty at the Battle of Muye. Many of the Shang soldiers went over to King Wu's side, because the Shang emperor, Di Xin, was unpopular.
Historians call the first period of Chou rule the Western Chou, because at this time the Chou only ruled the western part of modern China. China was divided up into about 200 little kingdoms, and then each of these kings was under the Chou emperor. Under each king were lesser lords, and these lords gave out land to individual farmers. In exchange, the lords collected some of the food as taxes.
During the Western Chou dynasty, the emperors ruled from great walled cities like those of the Shang Dynasty. Western Chou emperors relied on big strong armies to stay in power. These armies learned from Central Asia how to use a lot of chariots all together to win battles. The emperors led the armies out on campaigns almost every year, either fighting Central Asian invaders or keeping their kingdom together by preventing revolts. (Compare the Assyrians at the other end of Asia about the same time.)
To find out more about the Chou Dynasty, check out these books from Amazon or from your local library: