According to Mahayana tradition, the Mahayana sutras were transmitted in secret, came from other Buddhas or Bodhisattvas, or were preserved in non-human worlds because human beings at the time could not understand them:
ఏ సూత్రాలు మానవరహిత ప్రపంచాల లో భద్రపరచబడి ఉండవచ్చు?
Mahayana