Hi Joe... I`m new here... I saw in a book written by a historian named Takao Nakaya many years ago, Karate-Do History and Philosophy, where he points to the fact that "di" itself is a true Okinawan native art. There is no non-Okinawan influence within it(at least what I gathered from what I read). I hope I`m not misinterpreting but the earliest "di" is said to be from Tomari. There were no forms, just mainly grappling.
I`m sure this is information you already know.
Maybe you can find more info in the book I mentioned.