Purport

In this Shloka Bhagvan Shri Krishna describes the early stage of creation. At the beginning of creation 7 sages were created. For every Yuga there is one Manu who represents the primeval class of people in that Yuga.
Seven Rishis are
1. Marichi,
2. Atri,
3. Angiras,
4 Pulastya,
5 Pulah,
6 Kratu and
7 Vashishtha

And four manus for four yugas are
1. Svayambhu,
2. Svarochita,
3 Raivata and
4. Uttam

This to be noted that some of the sages listed are found in many yugas. That is because as per the earlier tradition, the son of Vashistha was called Vashistha, son of Vishvamitra was called vishvamitra etc. This tradition remained till very recently. As we all know, Chanakya. His real name was Vishugupta, Chanakya was an alias of Vishnugupta’s father and so he was also called Chanakya.

There are different manus for each yuga. This is to inform the classification of time of whole Kalpa is a complex one. A kalpa is a huge time period. Within Kalp exists Yugas, and within Yugas there exist sub-yugas, etc. That is the matter of separate discussion. As per the scriptures, 7 sages and Manus are formed of Lord Bramha. But the fact to understand is that the force, the power, and energy is still coming from Bhagvan Shri Krishna, that is why this Shloka uses ‘mam Bhava” which means with my power or my approval.