Another strain of thought dating to the Warring States Period is the school of yin-yang and the five elements.

The theories of this school attempt to explain the universe in terms of basic forces in nature, the complementary agents of yin (dark, cold, female, negative) and yang (light, hot, male, positive) and the five elements (water, fire, wood, metal, and earth).

In later periods these theories will come to have importance both in philosophy and in popular belief.