Dharmadhātu

Sanskrit: धर्मधातु

Tibetan: ཆོས་དབྱིངས་

Wylie: chos dbyings

Basic sense: the dimension of phenomena; the sphere of reality; the reality-field

Dharmadhātu means the true dimension of all phenomena—the way things actually are when not grasped as separate, solid, or self-existing. In Mahāyāna and Vajrayāna it often refers to the all-encompassing reality in which emptiness and appearance are not two. In Atiyoga usage, this is not some abstract absolute apart from lived immediacy, but the already-present nature of whatever arises.

Klong

Tibetan: ཀློང་

Wylie: klong

Basic sense: expanse, spacious dimension, vast openness, interior vastness

In Atiyoga, klong points to boundless openness, but not to a container-like space in which things are placed. It names the unobstructed expanse of reality itself—the openness in which manifestation is not other than emptiness. So when teachers speak of the “expanse,” they are not usually pointing to a background behind appearances, but to the unconfined nature of appearance-and-emptiness as inseparable. This is why it must not be reified into a subtle metaphysical substance or cosmic box.

Relationship between them

In many contexts, klong is a way of expressing the lived openness of dharmadhātu. If dharmadhātu is the reality-dimension, klong is its vastness, its unobstructed expanse. So the two are deeply related, but not quite the same in emphasis:

dharmadhātu stresses reality as such

klong stresses the open expanse of that reality

Put more simply: dharmadhātu names what is being pointed to; klong evokes how it is—vast, open, unbounded.

Ati Yoga nuance

The key is not to hear “expanse” as though phenomena arise inside a separate spiritual space. That would recreate duality. The expanse is not elsewhere than manifestation itself. Thoughts, feelings, perception, and the sense of self are not outside it, nor is there a watcher standing apart from it. In the cleaner language we have already been refining, there is no separate container and no contents standing apart from it; what appears is already not outside its own manifestness. This also fits the relational nuance we touched through James Low: openness is not withdrawal from appearance but availability to whatever arises.

Helpful formula

chos dbyings klong = “the expanse of the dharmadhātu”

This phrase brings the two together beautifully: the reality-dimension understood as vast, open, and unconfined.

Short memory line

Dharmadhātu is the reality-field.

Klong is its vast openness. ✨

If you’d like, I can turn this into your Ati Yoga Key Terms format next, with “core definition, mnemonic, common confusion it corrects, and contemplative glimpse.”