Was it the same vine? Are we speaking of the same body of work, e.g. Jonah's top sermons as delivered by Buddha?
Here's another transcontinental enlightenment situation - I was reading the B'Gita in a certain section when it became quite apparant to me that what I had before me were a series of admonitions taken from Proverbs. They'd been translated through a chain of several languages over the centuries, but there was no doubt this sacred Hindu literature was lifted from the Hebrew Bible. I then discovered that about the First Century C.E. there were Jewish missionaries who went to India to spread the faith. St. Thomas was among them, of course. In the end, Christianity was planted in India.
The various Hindu "popular" sacred texts that make up the B'Gita were assembled in that same period. The Jewish and Christian influence on those texts would not have happened had Christians adhered to a strict separation between themselves and the world of India.