The beginning of Taijiquan is as hazy as the mists which shroud the ancient mountains. There was an originator, but on this subject, there are at least two schools of thought. The legend says that Taijiquan was created by Chang San Feng, a Taoist sage and master of Shaolin Quan. Also according to legend, he witnessed a snake and a crane fighting (either while awake or in a dream) and combined this new style with his knowledge of Shaolin Quan, Taoist Qigong, the I Ching and the theory of Yin-Yang. From this legendary character comes the following lineage: Chang San Feng ----> Chang Sung Chi ----> Wang Tsung Yueh ----> Jiang Fa ----> Chen Chang Xin. Whether this is accurate or not is debatable.
Another school of thought states that Taijiquan can be only reliably traced to Chen Wang Ting. Either way, Taijiquan is undeniably linked to the Chen family. Those who say it was synthesized by the Chen family state that they combined the original Shaolin Cannon Pounding (Pao Chui), Shaolin Red Fist, and new elements to create Chen family style Taijiquan. The Chen family practiced five routines and the song contained 108 postures. By the time this art was commited to writing, two of the sets had been lost. From what can be traced back, it appears that the first set fist form, the fourth set, and the fifth set pounding fist persisted while the second and third sets were lost. The form has also changed somewhat over successive generations. Initially the forms consisted of what today is known as the Lao Jia (old frame) and the Pao Chui (cannon pounding). When this was passed to Chen You Pen (also spelled Chen You Ben), he changed it to create the Xin Jia (new frame). He taught this to Chen Ching Ping who also modified it somewhat to create Xiao Jia (small frame).
The Chen's Taijiquan taught by Master Yang is a mixture of Lao Jia (old frame) and Xiao Jia (small frame). He learned the Chen style from two different masters. He was taught by Wang Meng Bi who learned from Chen Fake who learned from his father, Chen Yen Hsi. Chen Fake was an ardent promoter of the Lao Jia in the early part of this century. He is also said to have taught a Xin Jia form in his later years which he created himself. This is why, as Adam Hsu points out, students from Chen Fake's early and later periods do Taiji differently.
In 1928, Grandmaster Liu went to Beijing to demonstrate his Baji/Piqua Martial Arts prowess. It was there that he witnessed a Martial Arts demonstration by the great Chen style master Chen Fake. He noted that the delivery of power and the stomping of the form performed by Master Fake closely resembled that of Baji. Out of a deep sense of mutual respect and goodwill, a private meeting was arranged between the two masters. During that time they exchanged the major principles and forms of their respective systems. They were both surprised to find that all of the primary jings trained for and developed in Baji Quan were also found in the Chen's style of Taijiquan. As a result of this common characteristic, GM Liu has always held the Chen's system of Taijiquan in high esteem and included it as part of the Wu Tang Martial Arts curriculum.
Master Yang also learned Chen style from Du Yu Ze (also spelled Du Yu Tse and Tu Yi Che). This lineage is as follows: Chen Chang Hsing (teacher of Yang Lu Chan, founder of Yang's style Taiji) taught Chen Kung Yuen who taught Chen Yen Hsi (or Chen Yen Xi, father of Chen Fake) who taught Tu Yu Ze. Tu Yu Ze learned from Chen Yen Hsi in his later years. At that time the art was still for the most part, a family secret. How Tu Yu Ze came to be included is as follows. Tu's father, Tu Yen was a government official in charge of the region containing the Chen village. Chen Yen Hsi worked as Tu Yen's bodyguard protecting his home and family as well. This gave Tu Yu Ze the opportunity to learn Lao Jia from him. Chen Yen Hsi's successor as security for Tu Yen and his family was Chen Ming Piao. He taught Tu Yu Ze another Chen style which he called Hu Lei Jia (thunder style). Master Tu Yu Ze died in 1990 at the age of 95.