Levels of Poptype randomness?

[Technowolf]

Hi all,

I was just wondering how truly random poptype selection is when generating a map. I could not find any information on how poptypes are chosen in the DB, but while perusing it one day I did come across some poptypes I had never seen before (i.e. Asmegs, vaetti w/ dwarves, toad tribals) or had never seen randomly placed (trolls, regular vaetti)

And before any asks, yes, I did use the search function, but could not find anything relating to this topic.