Aemilius: The sutras/suttas themselves first existed as oral tradition, so what is the difference?
The Buddhist tradition itself discriminates between shastras by Dharma sages and sutras that reflect most accurately Buddha's teachings. Therefore if it is not a sutra or sutta is less likely to be based on what Buddha taught, but may only be views that some of his disciples think
The thing is that if you are at the circle, or a follower of, a teacher say like Venerable Hsuan Hua, or Chögyam Trungpa, or any other Dharma teacher, you will get to know a lot of things
that the teacher has said and that he has done, and none of these are in the publicised teachings. These things that you hear, in various ordinary situations, are essential, are important. I am sure it has been similar during the early days of Gautama Buddha's Sangha or circle of followers. We can be sure there are important authentic things in the extra canonical oral teachings.
If you read the Ñanamoli Bhikkhu's translation of Vishuddhimagga you can get this feeling of genuine oral teachings, it certainly is there.
The Atanatiya Sutta
contains information about the mandala world view, the Four Great KIngs guard over the four sectors of the world, that is to say the eastern, southern, western and northern quarters. Thus the mandala world view is strongly implied, and even described a little, Mt Sumeru is Sineru in pali texts.
In the beginning of the Sutta there is a mandala of Deities with Gautama Buddha at the centre, and Yakkhas and Deities in the four quarters around him.