User blog comment:B214/Question and Answers 6/@comment-73.57.25.92-20180721185518

Just to let you all know, sirzechs story in highschool dxd zero, will be taking place 500 years in the past from the present days's story, meaning since this story take place in 20xx according to this(https://www.baka-tsuki.org/project/index.php?title=High_School_DxD:Volume_4_The_Festival_Ends), that means this story and the devil civil war takes place in the 1500's(https://en.wikipedia.org/wiki/16th_century) which is during the renaissance(https://en.wikipedia.org/wiki/Early_Renaissance), which would explain the creation of the evil pieces, since the renaissance was the age of new ideas.