Fajin,
I have wondered about the relationship between the kan and li practices of Taoism and the tummo practice of the six yogas. I have limited experience with both and am planning on studying the lesser kan and li this summer. I know that others have had some experience with both traditions on this site and I welcome their input on this topic.
In the Indian yogic system they have a practice called candali (also called the inner homa in some cases) which blazes and integrates the elements at the level of manipura chakra. This practice works with the five main prana of the body and dissolves them in the central channel at this junction point. The two main ones that are brought together are Prana vayu and Apana vayu. Prana vayu is upward moving and Apana vayu is naturally downward moving. Their natural movements are reversed and they are fused at the navel chakra. This fusion is said to ignite the inner fire and arose the latent vital energies of kundalini which are then used to purify the nadis and create a clear vessel or astral body. The tibetan tummo works much on the same process with the five vayus, yet they use a different chakra system. They still yoke the five pranas at the navel, however.(If anyone can offer insights on why their chakra system is set the way they have it, I would welcoem the discussion.) I have met practitioners that have attempted the tummo by learning it from books, and have fried themselves. It was as if they burnt up their jing. In some cases it was like they sucked it right out of their bones and now have rheumatoid disorders. I have wondered what has been left out of the books and how the ngondro serves to prepare the student for this practice. I have worked through about 3/5 ths of the ngondro and am curious about other practitioners’ experience that are working both systems. Thanks for asking the initial question, Pema