The set of practices that carries Naropa's name is a group of advanced tantric methods: the generation of inner heat, the recognition of the illusory nature of the body, the training of awareness during dreams, the practice of the clear light of sleep, the transference of consciousness at the moment of death, and the practice of the intermediate state after it. They are among the best known contents of Tibetan Buddhism and among the least publicly available, because in every lineage that holds them they are transmitted only with empowerment, preliminary training and a teacher, and that requirement is part of the teaching rather than an administrative rule around it. This atlas describes them and does not set them out.
The route is well documented. Naropa taught Marpa, the Tibetan translator who came south with gold to pay for instruction; Marpa carried the material home and taught Milarepa; and the whole Kagyu family of lineages descends from that transmission, with the Six Yogas as the completion stage practices at its core.
One honest qualification. The Six Yogas as a fixed and numbered set is a Tibetan formulation rather than something Naropa is known to have taught in that form, and the individual practices are attested across the Indian tantric literature independently of him. The name marks a channel of transmission, which is what a lineage is for.