In Mandala 4, Trasadasyu is the chieftain of the Purus. In addition to being the son of Purukutsa, Trasadasyu is also described as Gairikṣita, meaning descendant of Girikṣit. Trasadasyu lived on the western side of the Indus River (Sindhu) while Mandala 4 was being composed, but he also moved into the land of Seven Rivers and defeated the Anu-Druhyus and Yadu-Turvashas. He molded the conquered tribes and the Purus into the Pancha-janah (Five Peoples). To celebrate his victory he conducted an Ashvamedha with his horse, Dadhrikā. Dadhrikā is extolled in RV 4.38-40, and in these hymns, Dadhrikā is stated to have become a divine being, the sacrificial horse of the Ashvamedha, and a symbol of Puru and Indo-Aryan dominance. Trasadasyu's son was Tṛkṣi.