Ucchaishrava (उच्चैःश्रवस्)

Indra got a horse named Uccaihsravas from the Ocean of Milk. Uccaihsravas was one of the things got at the churning of Ksirabdhi (ocean of milk) (M.B. Adi Parva, Chapter 18 and Visnu Purana, Part 1, Chapter 9).

In the history of Bharata the period of Prthu's rule is considered a golden period. When Prthu became the emperor, Brahma divided the universe into several kingdoms and made a separate ruler for each of them. Soma was appointed King of the stars, planets, brahmins, plants, yagas and austerities. He appointed Kubera as the lord of Kings, Varuna as the lord of all waters, Visnu, as the lord of all adityas and Pavaka as the lord of all Vasus. Daksa was given lordship over prajapatis, Indra over maruts, and Prahlada over all daityas and danavas. Yama, the Dharmaraja was made lord of the manes. Airavata was made King of all elephants and Garuda King of all birds. Uccaissravas was made King of all horses and Vrsabha of all cattle. The lion was made King of all beasts and Himavan the lord of all immovable things. Kapila became chief of all sages and the tiger the leader of all beasts with nails and snouts. Plaksa was made the King of all trees. After distributing kingdoms thus, Brahma appointed Dikpalakas (guardians of the zones). In the east he posted Sudhanva, son of Vairajaprajapati, in the south he posted Sankhapada son of Kardamaprajapati, in the west he put Ketuman, son of Rajas and in the north Hiranyaroma. Thus Brahma organised a universe with suitable emperors to control and supervise. (Chapter 22, Am'a 1, Visnu Purana). (Page 609-610, Puranic Encyclopedia - Vettam Maṇi)