Yinang wuxing is one theory, while the doctrine of yinyang explains the interdependency of yin and yang, for example, hight (yang) can’t exist without a ground (low, yin). the doctrine of wuxing further interprets the regulation of the changes between yin and yang that manifest different things and phenomena, for example, water is cold (yin), when it gains heat (yang) it creates plants (wood). Wood has a nature of extending, which is yang, when it gains water (yin), it is flexible. When wood grows too fast, it drains the water (yin) and becomes dry. Dry wood easily turns into fire.
Although it is common to think of yinyang and wuxing as separate theories, without the concept of wuxing the theory of yinyang is merely a fixed and static idea that has no theoretical purpose in directing any practical activities. For example, if yin and yang are just two opposite entities, then cold and hot would have no connections or cooperations. In addition, if the concept of wuxing is separated from the concept of yinyang, then the doctrine of wuxing would also become just another quaint enigma. For example, without the concept of yinyang, the logic in wuxing that metal creates water would have made no sense.
See Yinyang Wuxing Spirit, Body & Healing for a more detailed explanation.