Problem being that other than Uechi, Higaonna and Matsumura, everyone before them is nothing more than mythological legends.
Several of the early pre-karate masters were gov't officials of one type or another, meaning there was some documentation. Sakugawa was one of the Ryukyu king's security agents, as was Matsumura. There was a contemporary article re: "The Oshima Incident" in which Kusanku was mentioned. There is not 100% certainty in much of early MA history.
There is also confusion about names as the principals often had 3 or 4 names they went by at any given point in their lives. Ryu Ru Ko may have been the same person as Xie Zhongxiang, or not. Most written records involving Okinawan MA history were destroyed during the carnage of WWll. So while proof is sketchy at times, it is sufficient, IMO, to establish a strong Chinese lineage.
There is no way around the fact that the okinawan forms are not Chinese forms and knowledge drift can not explain the difference.
Most of the Okinawan forms were constructed by those returning from China, adapting what they learned to their island's style of
te, or by their students, so few forms made it to the island in their original form. Often specifc techniques were extracted and put into new Okinawan forms. My understanding is that sesan (seisan) and sanchin (sa'am chien) kata can be found in a (barely) recognizable form in China today.
It is interesting to note that many Okinawan kata are written in katagana, the Japanese alphabet used for foreign words. If they were Okinawan originals, most likely they would be written in kanji/hiragana. This seems to give some credence to them being based on Chinese forms.
I wouldn't bet big money on any particular fact pre-1870 or so. I understand the possibility and power of myth. At the same time, all the stories and facts can't be wrong. I think enough of them have some basis in truth to support the major impact China had on karate's development.
if the okinawans learned Chinese arts as they proclaim why are they not teaching a second generation version of those arts with all the forms, herbal medicine, weapons and documentation
I have dealt with forms and documentation already. Chinese medicine, and culture in general, was studied by various Okinawan karate (and Japanese MA masters.) As for metal Chinese weapons, kobudo was mostly a seperate discipline from karate pre-Taira Shinken. Also, most of the guys we're talking about had some warrior background and were already trained on and familiar with the weapons they had. Metal was scarce on Okinawa, as were wars requiring them. Most were of wood, such as the
bo which Sakugawa was supposedly an expert in. All this, taken as a whole, may account for the lack of traditional Chinese weaponry.
I suspect the truth lies between our respective positions on this topic. Some facts, some suppositions, some guess work, and no doubt, some mythical stories all go into the mix regarding the roots of karate. It's all good, and perhaps other bits of info will be uncovered in the future.