Final answer:
The era when China was divided into many different kingdoms is known as the Warring States period, which occurred during 475–221 BCE.
Step-by-step explanation:
The era when China was divided into many different kingdoms is known as the Warring States period, which occurred during 475–221 BCE. During this time, the political power in China fragmented, and seven separate states emerged. These states were constantly at war with each other, engaging in traditional forms of power politics, forging alliances, making treaties, and fighting battles. Eventually, one state, Qin, emerged as the most powerful, leading to the end of the Warring States period.