Which came first, kata or embusen?

I can only answer this in a theoretical setting. The reason is there is "no data or historical documents/documentation" to provide us an answer. It is a very good question tho and I am going to answer it only from my personal views and knowledge, as minimalistic as that is.

The kata came first. My belief is that those who came before, the creators of karate as derived from the original indigenous practice of toudi or ti, pulled together their techniques and along with their studies of the Chinese arts of the fist, Chinese boxing, they created their kata.

Lets take it back a bit and try to understand how karate came to be. Okinawa had some form of fighting system which came to be known as "Ti" which is Okinawan dialect for Te or hand if you will. It is also believed that it was referred to as "toudi" or a type of wrestling/grappling/striking system [this is arguable/debatable of course].

The Okinawan's relied heavily on trade with other countries for their livelihood. Their primary sources and influences were Chinese. The trade and exchange with the Chinese is well documented in the only English history book we have and other information/documentation is simply hypothesis by Americans, etc.

The Chinese influences permeated all aspects of life on Okinawa barring the one trait that seems to be exclusive to them, their gentlemanly nature; their peaceful way of politeness and decorum they expressed to anyone and everyone be they friends or conquerors.

The Chinese influences were very strong regarding Okinawan fighting systems in that Chinese boxing was a part of the relations both countries enjoyed for many, many years. We hear stories of Okinawan's traveling to China to learn Chinese boxing which we call "kung fu."

The Chinese already had patterns for practice which we call kata so that in all likelihood influenced Okinawan masters of their systems to incorporate these patterns of fighting into a "kata." We may have found if it were actually documented that they were not called "kata" then but some other Uchinaguchi term, i.e. this is the Okinawan dialect of language.

The Chinese had a name they called the forms or rather the movements, i.e. "Eighteen Movements of Lohan (Order 26). These techniques are thought to be the basis of the modern martial arts and the true origin of Shaolin Kung Fu," as stated here, " http://blog.gronski.org/2010/12/origins-of-shaolin-kung-fu-history-of-the-various-forms/ "

So, regarding karate of Okinawa, the kata came first and the patterns of movements where embusen are formed by the practice came to be and who knows when those lines or blueprints of kata came to be called embusen. I can extrapolate that it might have come from Japanese influences but suspect it actually came from the implementation of the "sportive aspects" and the "implementation to school systems" effort.

Most who refer to embusen tend to connect it to the tournament efforts for start/stop and evaluation grading in competitions.

So, what do you feel is the source and purpose of embusen? The one caveat I would express here and all the time is all information must be taken as theory simply because very little was actually documented for historical purposes. I my humble opinion documentation of any kind concerning karate did not come to fruition until the late 1800's but more in the 1900's after WWII.