There was no martial art referred to as Taijiquan before Chen Wangting 1580 - 1660. There is likely a Qigiong form referred to as taiji qigong prior to that, but nothing called Taijiquan as a martial art pre Chen Wangting. There are multiple references to Zhang Sanfeng, who may or may not have existed, but there is no verifiable historical proof that he did. There is also a possibility that there was something similar to the 13 postures prior to Chen, but again that cannot be proven.
Number of postures from the Chen family, likely a lot more than 27. There is speculation that Chen Wanting came up with one Chen family taijiquan form that was later split into Laojia Yilu and Laojia Erlu.
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Zhang Sanfeng was REAL!!! well noÂ…