Each of them taught extensively, founding groups teaching T'ai chi to this day. Cheng Man-ch'ing, perhaps the most famous outside of China, significantly shortened and simplified the traditional forms Yang taught him after his teacher's passing, reportedly to make them more accessible to larger numbers of students. Although Cheng's modifications are considered controversial by most other schools and are not recognized by the Yang family, Cheng Man-ch'ing is known as one of the first to teach T'ai chi ch'uan in the West.