We have already discussed the incarnations of Manu in the First Canto. In one day of Brahmā there are fourteen Manus, changing one after another. In that way there are 420 Manus in a month of Brahmā and 5,040 Manus in one year of Brahmā. Brahmā lives for one hundred years according to his calculation, and as such there are 504,000 Manus in the jurisdiction of one Brahmā. There are innumerable Brahmās, and all of them live only during one breathing period of Mahā-Viṣṇu. So we can just imagine how the incarnations of the Supreme Lord work all over the material worlds, which comprehend only one-fourth of the total energy of the Supreme Personality of Godhead.
The manvantara incarnation chastises all the miscreant rulers of different planets with as much power as that of the Supreme Personality of Godhead, who punishes the miscreants with His wheel weapon. The manvantara incarnations disseminate the transcendental glories of the Lord.