Srimad Bhagavatam Canto 12, Chapter 07, Text 16

SB 12.7.16

rajñam brahma-prasutanam
 vamsas trai-kaliko ’nvayah
vamsanucaritam tesam
 vrttam vamsa-dharas ca ye
 
Translation: 
 
Dynasties are lines of kings originating with Lord Brahma and extending continuously through past, present and future. The accounts of such dynasties, especially of their most prominent members, constitute the subject of dynastic history.
Srimad Bhagavatam Canto 12, Chapter 07, Text 15
Srimad Bhagavatam Canto 12, Chapter 07, Text 17