Eastern Zhou Dynasty
In 771 BC, skillful fighters from the northwest invaded China; they may have been the ancestors of the Huns. The Zhou emperors retreated and made a new capital at Luoyang, further east. So this period is called the Eastern Zhou.
People call the first three hundred years of the Eastern Zhou period the Spring and Autumn period because it was a good time for China. Many philosophers, like Confucius and Lao-Tzu, were working in China at this time. Tool-makers in China learned how to use iron to make tools at this time; they probably learned from iron-workers in West Asia, maybe by way of India or Central Asia.
But iron also made good weapons, and the 200 little states began to fight each other all the time. The period from 481 to 221 BC is called the Warring States period. By about 300 BC, there were only seven big states left. By 256 BC, the Zhou emperors lost power, and the only rulers of China were the kings of the seven states. These kings fought among themselves until the king of Ch'in, the strongest state, succeeded in making himself emperor and established the Ch'in Dynasty.