The Great Ages of Man set was published in the late 60's. These books were the pre-cursor to many of the series printed in the 70's and 80's, and they seemed to establish or reinforce most of the precedents you see with these books.
I actually own a complete set of these books, though I've only had time to read one (Byzantium). The volume I read was very well done, but there aren't too many other books out there to compare it to. In all, though, this is a very nice set.
I have heard from some people that the volume listed as Barbarian Europe was originally called The Birth of Europe, but this might be another case of having one title in the US and one title outside the US.