Thanks. So, would you say that Chen old frame first sequence would have been the first post-thirteen postures form that could be called taijiquan?
I honestly don’t know and I don’t know who could answer that with 100% certainty.
There are some in Chen that say Chen does not have the 13 postures that is a Yang thing. And then there are those in Chen that teach them. Now it could be that they are simply saying there is nothing in Chen called the 13 postures but there are the 5 Steps, 8 Techniques and 5 Elements, which is possible since there was, at one time, definite push to have a separation between the styles from both families. Or it could be they did not separate them from the form, or it could be lineage.
But if you look at what I have seen billed as the 13 postures of Chen style, like Yang, almost all of them are in Laojia Yilu (almost all in the Yang long form). My Yang sifu acknowledges their existence, points them out in the long form, but does not teach them separately but I think (and I am not 100% sure of this either) some do (or did) teach them separately.
My speculation on the origin of taijiquan, and it is just a speculation, is that somewhere someone combined Shaolin Paoqui with an older Qigong that was called Taiji Tao Yin (or whatever qigong was called then) with something that may or may not have come from a Taoist that was similar to the 13 postures but there were likely more postures (There has been some speculation by Chinese historians that there was something similar but it was 28 or 56 or some number bigger than 13) now throw in whatever the Chen family was practicing at the time (and that might be where the Paoqui comes in, or it might not be) and a dash of Taoist philosophy (I-Ching, but that might have already been there) and voila you have Chen Taijiquan…or whatever they called it, as late as Chen Fake he was not categorizing it as Taiji he was calling it Chen family martial art. But then Yang Luchan did not call it Taijiquan either. That categorization (name) came from , if my memory is working this morning, Wu Quanyou (1834–1902), or his son Wu Chien-ch'uan (1870–1942) who where students of Yang Luchan, or Yang Banhou (depending on whose lineage story you want to believe)
One last thing and I stop rambling. There has also been some conversation about the original Chen family form, from Chen Wangting, of Taijiquan not being Loajia Yilu and Laojia Erlu but a longer form that was later split and that is where Loajia Yilu and Erlu come from.
So ultimately, like most things Taijiquan history, the answer is a resounding….aaaaa…maybe