User blog comment:Khalael/Space Marine Chapter Foundings/@comment-3562230-20120503212039/@comment-4608429-20120503230744

It's not whether it was recorded or not, but whether or not their records have been lost through time. And sometimes you have to make them unknown but having a suposid founding, for instance their can be no 13th founding chapters, as their are only two known chapters from this founding.