What scholars definitely know is that sages in India had an extraordinary power to memorize sacred texts. My professor at Harvard used to say that when we listen to Brahmanas reciting the huge Rg-Veda, it’s just like listening to an ancient tape recording because they preserved every syllable and phoneme. In comparison, the Gita is a very small text, and any child in that culture could memorize it. Further, because of the Gita’s importance, it would have been memorized. So in police language, we have a motive to perfectly memorize it, and the means to carry it out. And that’s what happened. Writing began in India a little over 2 thousand years ago, and so it was quite simple to write down a Gita which had long been memorized and recited. We don’t know who first physically wrote it down. Probably there were multiple scribes.