It is a kind of yajña (yajna). In the beginning of creation, this yajña (yajna) emerged from the southward face or Brahmā, or in another view, from his eastward face.

Ukthya is one of the seven types of ancient Jyotiṣṭoma yajña (Jyotishtoma yajna). In fact, it is a vikṛti (vikriti) of Jyotiṣṭoma yāga. In Ukthya yāga (yaga), after twelve scripture-reading in three savana(s), extra three scriptures are read by the three assistants of Hotā (Hota; the chief priest). So, in Ukthya yāga, there are fifteen śāstra(s), and therefore fifteen stotra(s). In this yāga, there are two animals given to sacrifice — one goat is sacrificed to Agni, and another is sacrificed to Agni and Indra.

Though there is no specific mention of Ukthya in Mahābhārata (Mahabharata), there is a mention of Saptasaṃsthā Somayāga (Saptasamstha Somayaga), in the context of the yajña performed by the famous Aṅgarāja. Ukthya is a type of that Saptasaṃsthā Somayāga. Again, in Droṇaparva, in context of the yajña performed by king Yayāti, yāga(s) like Atirātra (Atiratra), Cāturmāṣya (Chaturmasya) and Agniṣṭoma (Agnistoma) are mentioned. So, naturally Ukthya comes in, as a type of Agniṣṭoma. In Rāmāyaṇa (Ramayana), however, the mention of Ukthya is clear enough. In the description of the Aśvamedha yajña (Aswamedha yajna)of Daśaratha (Dasaratha), according to Kalpasūtra (Kalpasutra), it is said that on the first day Agniṣṭoma, Ukthya savana on the second, Atirātra on the third — different types of yāga were performed in this order. From these instances, it is clear that in the time of Rāmāyaṇa and Mahābhārata, the importance of yajña(s) did not reduce, and Vedic yajña(s) were still given high esteem.