Ajina is skin in general and the skin of a black antelope in particular. Hence the name kṛṣṇājina. Throughout the ages it has been a symbol of holiness and Vedic culture. Even the country Āryāvarta, has been defined as the territory where kṛṣṇamṛga or the black antelope wanders freely. The Śatapatha Brāhmaṇa (1.1.4. 1-2) compares yajña (sacrifice) to a black antelope with white, black and yellow hair representing respectively the Ṛk, Sāman and Yajus.
Being considered holy, it is often used in sacrificial rites for various purposes as in husking grains from which cakes are made.
It is used by the brahmacārin (celibate novice pursuing the Vedic studies) and the yati or muni (ascetic) as a seat or spread or a couch.
A strip of kṛṣṇājina used to be worn by the dvijas in the earlier days as yajñopavīta (sacred thread) which was later replaced by the thread.