* Economic development: The Warring States period saw a period of rapid economic growth, which led to increased competition for resources and power. This competition often resulted in conflict.
* Social change: The Warring States period also saw a period of significant social change, as new classes and groups emerged and vied for power. This social change often led to conflict.
* Political instability: The Warring States period was also marked by political instability, as the Zhou Dynasty declined and various states competed for power. This political instability often led to conflict.
External causes:
* Foreign invasion: The Warring States period saw a period of increased foreign invasion, as various nomadic tribes from the north and west invaded China. These invasions often led to conflict.
* Climate change: The Warring States period also saw a period of significant climate change, as the Yellow River shifted course and caused widespread flooding and drought. This climate change often led to conflict.
In summary, the Warring States period was a time of great change and upheaval in China, and these changes often led to conflict. The Warring States period ended in 221 BC, when Qin Shi Huang unified China and established the Qin Dynasty.