Amok lore question

Where the fuck do these guys come from? Played the dlc twice and I feel like they just don’t explain them at all, like first playthrough I thought there was only one ( clearly not the case ) are they forced to stay in iron forest / cnpp? How many of them are there? I believe they were made during the project x and we visited that lab with all the cages and shit, is there where they were made? Is there more info on them like did I miss some lore pick ups or something.