This chapter of the Srimad Bhagavatam describes the extremely large number of Yadavas who lived during the time of Krishna:
I have heard from authoritative sources that the Yadu family employed 38,800,000 teachers just to educate their children. Who can count all the great Yādavas, when among them King Ugrasena alone was accompanied by an entourage of thirty trillion attendants?
But of course there were more humans at the time than just Yadavas. So my question is, what the total number of humans in the world at the time of Krishna?
Or if that isn’t described in Hindu scripture, are there any scriptures that speak about the total number of humans in the world in some other time in a previous Yuga?
Note that I don’t want scientific speculation, I just want to know what Hindu scripture says on the subject.