Dharmadhatu (Sanskrit) is the 'dimension', 'realm' or 'sphere' (dhatu) of the Dharma or Absolute Reality.
In Mahayana Buddhism, dharmadhātu (Standard Tibetan: chos kyi dbyings; Chinese: 法界) means "realm of phenomena", "realm of Truth", and of the noumenon. It is referred to by several synonymous terms from Mahayana Buddhist philosophy, such as Tathata (Reality "as-it-is"), emptiness, dependent co-arising and eternal Buddha. It is the "deepest nature, or essence".
Dharmadhātu is the purified mind in its natural state, free of obscurations. It is the essence-quality or nature of mind, the fundamental ground of consciousness of the trikaya, which is accessed via the mindstream.
When the buddha-nature has been realised, dharmadhātu is also referred to as the Dharmakāya, the Body of Dharma Truth.
It is associated with Vairocana.
Kang-nam Oh traces the origin of dharmadhatu to the Avatamsaka Sutra. It has been further developed by the Hua-yen school:
Dharma Realm Buddhist University (DRBU) is an American private not-for-profit university located in Ukiah, California, established in 1976 by Venerable Master Hsuan Hua. It is situated within a monastic setting of the City of Ten Thousand Buddhas, and is the only college in the Western Hemisphere to offer the experiences of daily practices of a Mahayana Buddhist monastery. Students explore the close interaction between the theory and practice of Buddhism as embodied in its monastic form. The university has a longstanding partnership with the Pacific School of Religion and the Graduate Theological Union, as well the Dharma Realm Buddhist Association.
On October 2, 1976, Dharma Realm Buddhist University was formally established at the City of Ten Thousand Buddhas, with the very first class arriving in 1977. The first Chancellor was Venerable Master Hsuan Hua. In 1976, the Institute of World Religions was created by Venerable Master Hsuan Hua and Paul Cardinal Yu Bin. In 1986, DRBU hosted the Conference on World Religions for the first time in California. In 1994, the Institute of World Religions moved to Berkeley Buddhist Monastery. In 1997, DRBU began its partnership with the Graduate Theological Union and Pacific School of Religion. In 2000, the Venerable Master Hua Memorial Lecture series began. In 2001, the Institute for World Religions published the inaugural issue of the academic journal, Religion East & West. In 2006, DRBU established the Berkeley campus with Venerable Heng Sure, Ph.D., as its first director. In 2011, DRBU launched the University blog, dharmas .