Bhagavatapurana 3.11.24

3.11.24

svaṃ svaṃ kālaṃ manur bhuṅkte sādhikāṃ hy eka-saptatim /
manvantareṣu manavas tad-vaṃśyā ṛṣayaḥ surāḥ /
bhavanti caiva yugapat sureśāś cānu ye ca tān //

24. Each Manu enjoys the power during the period alloted to him, which is a little over seventy-one Chatur Yugas. During the Manvantaras the several Manus, their descendants, the Rishis, the great gods and their attendants are all born together.