Taoist philosophy is best known from ancient texts which have become popular in the Western world. The "Tao-te-Ching" and "I-Ching" are examples. This philosophy was developed as people began developing the principles of civilization such as the relationship between the ruler and the people. While Confucianism emphasized regulating human behavior on the basis of a hierarchical order of authority, Taoism emphasized regulating behavior to conform to natural principles. Nature was considered the authority. A life and a society lived simply and naturally was considered to be the best for all people. The two philosophies were complementary though many Taoist texts enjoyed pointing out what they considered to be the shortcomings of Confucianism. While Confucianism was dominant in the cities, Taoists tended to live in rural areas.
Taoists observed the cyclic changes of nature, as do other rural people, and thought of nature as in a state of dynamic equilibrium. Seasons may constantly change, but they do so in a cycle, always returning to the beginning. Urban people tend to see their lives as moving in one direction only, that of continued progress. An urban area is also changing but usually does not return to a previous state, unless there is war or decay.
The yin/yang symbol of the Taoists, depicting two fish-like figures swirling around each other, is the symbol of Taoism. The symbol is in the form of a circle, the strongest and most stable geometric figure. The circle (strength and stability) and the swirling fish (cyclic motion) are a very simple and easy to understand symbol of nature herself.
The Taoists consider humans to be nature as well and our bodies as an ecological environment. In Taoist forms of healing the emphasis of diagnosis is on how all of the body parts are interacting, not on what is wrong with a single part. By watching the ecological environment it is easy to see the interrelatedness of all life. The body was likewise seen as an interrelated system of many parts. They focused on relationships for healing. The relationship among the body parts was seen as directly affected by the relationship of a person with other people and with nature. How you are getting along with your family is equally as important for diagnosis as the condition of one organ.
While the earliest writing of Taoism, the Yellow Emperor's Medical Texts, were printed around 4,500 years ago (the time the Chinese written language was formed), Taoism probably goes back a lot further. But it is hard to know what really went on before that first written text. You could really say that Taoism is the philosophy that any people would have who lived close to nature.