SB 9.3.32
tat putra-pautra-naptrnam
gotrani ca na srnmahe
kalo ’bhiyatas tri-nava-
catur-yuga-vikalpitah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Twenty-seven catur-yugas have already passed. Those upon whom you may have decided are now gone, and so are their sons, grandsons and other descendants. You cannot even hear about their names.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
During Lord Brahma’s day, fourteen Manus or one thousand maha-yugas pass away. Brahma informed King Kakudmi that twenty-seven maha-yugas, each consisting of the four periods Satya, Treta, Dvapara and Kali, had already passed. All the kings and other great personalities born in those yugas had now departed from memory into obscurity. This is the way of time as it moves through past, present and future.