Asvamedha was a Hindu, Vedic, ritual of horse sacrifice. It was performed by kings as a symbolic representation of their supreme power and authority, and, sometimes, for such blessings as the birth of a son to ensure succession. For the previous year the chosen horse wondered unmolested as he pleased in a pasture while protected by an armed guard.
If he trespassed into another kingdom, the ruler was obliged to fight to keep the animal or surrender him. At the end of year the animal was brought back to the capital with appropriate ceremony, and sacrificed along with other animals. The fertility of this ceremony is evident from the way in which, symbolically, the senior queen would lie beside the dead horse. Jaya Sinah II of Jaipur was the last prince to perform this ceremony in the 18th century. A.G.H.
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, p. 103