This are very complicated structures, so I'm not to sure, but I don't think either of them are relative clauses. They are related to previously mentioned things in the paragraphs, but they are stand alone and they don't have a relative pronoun connecting them (who, whom, which, whoever, whomever, whichever, or that).
"... something about migrations of people who lived long ago"
'who lived long ago' is an example of a (defining) relative clause, but I don't think the phrases you pulled out are.