The 13th chapter starts with Vidura inquiring about the activities of Svāyambhuva Manu and Śatarūpā. In the last verses of the previous chapters, their activities were described in summary, and now Vidura wants to know in detail.
The appearance of Svāyambhuva Manu is an important event in the creation of the universe because it marks the start of the first manvantara.
There are 14 manus in a day of Brahma, in a sequence that repeats in each of his days. At the end of each manvantara, a great process of extinction occurs, with the previous Manu and all demigods leaving their posts. After a long period of managing the universe (a Manvantara lasts for 306.72 million years), these demigods receive the opportunity of being promoted to Maharloka, from where they continue gradually progressing.
Srimad Bhagavatam #24: The cycles of the Manus