In the process of the development of TCM theories, the physicians of generations developed the theoretical system of TCM from different aspects by summarizing their own experience in clinical practice and researching systematically the theoretical viewpoints on the basis of Canon of Medicine（Nei Jing）, Treatise on Cold Damage and Miscellaneous（Shang Han Za BingLun）and other ancient classics.
The period of Wei, Jin, Sui and Tang Dynasties
The characteristics of this period include two aspects: one is continuing to elucidate the theories; the other is emphasizing the importance of summarizing the clinical experience. In particular, the meridian and collateral theory, the pulse theory and the pathogenesis theory are further developed in this period.A-B Classic of acupuncture and Moxibustion（Zhen JiuJia Yi Jing）, written by HuangfuMi, a noted physician in Jin dynasty, is the earliest monograph of acupuncture and moxibustion in China. It made in-depth discussions on the meridian and collateral theory and systematic exposition of visceral manifestations, meridians and collaterals, acupoints, specimens, nine kinds of needles, needling methods, diagnostic methods, syndromes and treating methods, etc., and thus laid an important foundation for the development of acupuncture and moxibustion in later ages.PulseClassic（Mai Jing）, written by WangShuhe, laid the foundation of the pulse theory and the systematicness and standardization of the methods of pulse diagnosis. It is the first monograph on pulse theory in China. Treatise on the Pathogenesis and Manifestations of AllDiseases（Zhu Bing Yuan HouLun）, written by Chao Yuanfang, a physician in Sui dynasty, is the first monograph on the aetiology, pathogenesis theory and syndrome theory of traditional Chinese medicine. It discusses in detail the causes and symptoms of many diseases and thus has a significance for the later development of aetiology and pathogenesis theory.InvaluablePrescriptions for Emergencies（Qian JinYao Fang）and Supplement to InvaluablePrescriptions for Emergencies（Qian Jin YiFang）were written by Sun Simiao, the famous physician in Tang dynasty. They give a detailed description of the medical theories, prescriptions, diagnostic methods, treating methods and health-preserving by food before the Tang dynasty. Their rich contents can represent the advanced medical level and achievements of the flourishing Tang dynasty. They together are called invaluable Prescriptions（Qian JinFang）, which is the first medical encyclopedia of China.
The period of Song, Jin and Yuan Dynasties
The characteristics of this period are the rapid development of medicine, the appearance of many medical schools and the outstanding achievements, which have a great influence on the development of medicine in later ages. Many physicians combined their own practical experience with the achievements inherited from the former generations to make some innovations and present many original opinions, so that the traditional Chinese medicine had a new breakthrough in this period. In the Song dynasty, Qian Yi wrote Key to Therapeutics of Children's Diseases（XiaoEr Yao Zheng Zhi Jue）, which first advocated the treatment based on syndrome differentiation of Zang-fu organs. Chen Yan wrote Treatise on the Three Categories of Pathogenic Factors and Prescriptions（San Yin Ji Yi BingZheng Fang Lun）and proposed the famous"theory of three causes", which made a more specific classification and summary of the causes of diseases.
In Jin and Yuan dynasties, Liu Wansu, Zhang Congzheng, Li Gao and ZhuZhenheng made an important contribution to the development of the theories of traditional Chinese medicine, so they were known as"the four great medical experts in Jin and Yuan dynasties". Liu Wansu was influenced by the theory of yun qi（a theory for the ancients to study the climate change and to discover the relationship between human health and diseases）and so he emphasized that"six qi, including wind, cold, summer heat, dampness, dryness and fire（heat）, all can be transformed into the pathogenic fire" and"excess of the five emotions-excessive anger, joy, grief, thought and fear can result in pathogenic heat".Therefore, the pathogenesis of fire and heat was further elucidated. Zhang Congzheng thought that the diseases were caused by pathogenic factors and a patient would be cured if the pathogenic factors were removed. He advocated using diaphoresis, emesis and purgation to remove the pathogenic factors. Li Gao presented the viewpoint that"dysfunction of spleen and stomach is the reason for many diseases", he thought that most of the diseases were caused by the dysfunction of spleen and stomach. Zhu Zhenheng developed the theory of ministerial fire; he thought that the yin was often excessive while the yang was often deficient, so he advocated nourishing yin and purging fire.
The period of Ming and Qing dynasties
This is an important period for the academic development of traditional Chinese medicine. The contributions of the physicians and pharmacologists include two aspects: one is sorting out the medical achievements and clinical experience and compiling a wide range of medical books, classified medical books, medical collections and notes on medical classics, etc. The other is the formation of the warm heat theory and the school of warm disease, showing the significant innovation and invention in the medical theories and methods. The school of heat cation, represented by Xue Ji and Zhang Jiebin, emphasized the great importance of the spleen and kidney and formed the theory of life gate, in which the life gate was thought of as a place to hold yin and yang, fire and water, the root of the yin and yang of zang-fu organs and the hub of regulating yin and yang of the whole body. Li Zhongzi proposed the viewpoints that"the kidney is the origin of the congenital constitution, while the spleen is the root of after-birth", making a new contribution to the development of the theories of traditional Chinese medicine, especially the theory of visceral manifestation.
The formation and development of the theory of warm disease is an innovative breakthrough in traditional Chinese medicine theory. The theory of warm disease originated from Canon of Medicine（Nei Jing）, Classic of Difficult Issues（Nan Jing）and Treatise on Cold Damage and Miscellaneous（Shang HanZa Bing Lun）, replenished and developed constantly by generations of physicians, and reached maturity in the period offing and Qing dynasties. In Ming dynasty, Wu Youke wrote Treatise on Pestilence（Wen Yi Lun）and first put forward the theory of"pestilential qi".He pointed out that plague attacked the human body by way of the nose and mouth.In Qing dynasty, Ye Tianshi wrote Treatise on Warm Heat Disease（Wen ReLun）, developed the theory of defence, qi, nutrient and blood, and initiated defence, qi, nutrient and blood syndrome differentiation; Wu Jutong wrote Systematized Identification of Warm Diseases（Wen Bing Tiao Bian）and created triple energizer syndrome differentiation for warm diseases; XueShengbai wrote Chapter of Damp Heat Diseases（Shi Re Bing Pian）and proposed the original viewpoint that"damp heat diseases are not only different from febrile diseases but also different from warm diseases"; WangMengying wrote Warp and Weft of Warm Heat Disease（Wen Re Jing Wei）. These books systematically summarized the pathogenic mechanism of the exogenous infectious febrile diseases, made a breakthrough in the traditional concept that"warm disease theory is developed on the basis of febrile disease theory", and created the syndrome differentiation and treatment of warm heat diseases mainly based on defence, qi, nutrient and blood syndrome differentiation and triple energizer syndrome differentiation so that the warm heat disease theory has formed a complete theoretical system in the aetiology, pathogenesis, and syndrome differentiation and treatment. In addition, Wang Qingren, a physician of Qing dynasty, attached great importance to anatomy, and he wrote Correction of errors in Medical Classics（Yi Lin GaiCuo）, in which he corrected the errors of human anatomy in the ancient medical classics and developed the theory of blood stasis causing diseases and the treating methods for diseases caused by blood stasis, making a certain contribution to the development of the basic theories of TCM.