130K unknown indexed pages?

I just bought a new domain and put it on a search console and left it for 2 months but when I came back and checked, lo and behold its got 130k indexed links but not submitted in the sitemap. It even has a few thousand impressions and dozens of clicks to pages that the previous owner made and doesn't exist since I only installed WordPress and 1 page has no post yet. What's next guys?

Rebuild the site to gather that traffic and links back and move on from there.

GenesisOne said:

Rebuild the site to gather that traffic and links back and move on from there.

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I'm a bit confused, do you mean I should use these links for traffic? How? Im newbie