Aśva (Aswa) means horse. In Purāṇa(Purana; Mythological Scripture) it is said that domestic animals like horses emanated from the body of Brahmā (Brahma) in the beginning of Tretāyuga (Tretayuga).
Elsewhere it is said that Sugrīvī (Sugrivi) was one of the daughters born of the womb of Tāmrā (Tamra), daughter of Dakṣa (Daksha), and sired by Kaśyapa(Kasyapa) Prajāpati (Prajapati; Ruler of the people). This Sugrīvī gave birth to horses, camels and donkeys.