Six Lokas refers to a Bönpo and Nyingmapa spiritual practice or discipline that works with chakras and the six loka that is dimensions or planes as well as the six classes of sentient beings in the Bhavachakra. Various traditions of the sadhana also include mindstream elements. Tenzin Wangyal Rinpoche and Chögyal Namkai Norbu Rinpoche have published literature and teach versions of the sadhana or practice. For both of these versions the six lokas are cognate with the principal six chakra system of Vajrayana. Tenzin Wangyal Rinpoche states that: The Six Lokas can be divided into six realms: