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SB 5.1.28

anyasyām api jāyāyāṁ trayaḥ putrā āsann uttamas tāmaso raivata iti manvantarādhipatayaḥ.
Synonyms: 
anyasyām — other; api — also; jāyāyām — in the wife; trayaḥ — three; putrāḥ — sons; āsan — there were; uttamaḥ tāmasaḥ raivataḥ — Uttama, Tāmasa and Raivata; iti — thus; manu-antara — of the manvantara millennium; adhipatayaḥ — rulers.
Translation: 
In his other wife, Mahārāja Priyavrata begot three sons, named Uttama, Tāmasa and Raivata. All of them later took charge of manvantara millenniums.
Purport: 

In every day of Brahmā there are fourteen manvantaras. The duration of one manvantara, the life span of one Manu, is seventy-one yugas, and each yuga is 4,320,000 years. Almost all the Manus selected to rule the manvantaras came from the family of Mahārāja Priyavrata. Three of them are particularly mentioned herein, namely Uttama, Tāmasa and Raivata.