anyasyam api jayayam trayah putra asann uttamas tamaso raivata iti manvantaradhipatayah.
anyasyam—other; api—also; jayayam—in the wife; trayah—three; putrah—sons; asan—there were; uttamah tamasah raivatah—Uttama, Tamasa and Raivata; iti—thus; manu-antara—of the manvantara millennium; adhipatayah—rulers.
In his other wife, Maharaja Priyavrata begot three sons, named Uttama, Tamasa and Raivata. All of them later took charge of manvantara millenniums.
In every day of Brahma there are fourteen manvantaras. The duration of one manvantara, the lifespan 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 Maharaja Priyavrata. Three of them are particularly mentioned herein, namely Uttama, Tamasa and Raivata.
Link to this page: https://prabhupadabooks.com/sb/5/1/28