So for those people wondering what is up with episode numbering in season 5 - 10, know that the info comes from tvdb. There the principle is that numbering is based on original numbering - but as far as I understand History channel decided to renumber episodes from s5-s8 and spread them out so they became s5-s10. And then the started making episodes named from s11. So according to original numbering there is no s9 and s10, but after the renumbering there.

Go to thetvdb and you will see that s9+s10 is not there. It seems that s9+s10 was imported into trakt.tv anyhow so that means that s9+s10 now duplicates episodes from the previous seasons. Update Aug2020: trakt.tv now correctly removed season 9 and 10.

See more in this discussion (among many) on tvdb forums: https://forums.thetvdb.com/viewtopic.php?f=18&t=29976

I gave this a 3/10 review, why?: I think some episodes are ok, but there is much recycled content across the series it just seems very lazy. So much repetition. And then I really do like that none of the episodes go in depth with their so-called evidence. Show us the texts! And explain the science in greater detail! Show us the full original reports instead of superficial second hand stories by untrustworthy pseudo historians. This could have been so much better.