One of the Vedic sacrifices mentioned often by the purāṇas, the Rājasūya (-yāga), could be performed only by a kṣattriya or a king.
Some authorities opined that it could be performed after the Vājapeya (another well-known sacrifice) while others felt that it should be done before. The Śatapatha Brāhmaṇa (22.214.171.124) declares that one who performs the Rājasūya becomes a rājan (king) whereas the performer of the Vājapeya becomes a saṁrāṭ (emperor).
It is a rite of royal consecration and lasts for more than two years.
The yajamāna or the sacrificer has to take the dīkṣā or preliminary vows on Phālguna-śukla-pratipad (first day of the bright half of the month of Phālguna, generally in February/March). He then performs a Soma sacrifice called the Pavitra. The procedure for this is the same as for the Agniṣṭoma sacrifice. (See AGNIṢṬOMA for details.)
This is then followed by a series of iṣṭis (sacrifices performed with oblatory materials like ghee and porridge) like Anumati, Cāturmāsya, Apāmārgahoma (a rite to drive away demons) and so on.
The most important part of the Rājasūya is the Abhiṣecanīya rite (the rite of unction lasting for five days) wherein the water for the abhiṣeka (the act of pouring the water on the head) has to be brought from seventeen sources, kept in seventeen vessels of udumbara wood (Ficus glomearata) and poured on the sacrificer’s (the king’s) head by several persons including the commoners.
Then there is a symbolic march for the plunder of cows. A group of one hundred cows is ‘seized’ by the king and then given back to their owners.
A dice-play in which the sacrificer-king always wins is also a part of the ritual.
As in other sacrifices, the sacrificer has to take the avabhṛthasnāna or the concluding bath.
The fees prescribed for this sacrifice is extremely heavy—2,40,000 cows, to the various priests.
The Pāṇḍavas are said to have performed this sacrifice in Indraprastha, their capital (vide Mahābhārata, Sabhā-parva chs. 33-45).