User blog comment:Dark Lord Mairon/Could Arda be Our World before it was created?/@comment-26116279-20150904112327/@comment-25869554-20150904163651

Around the start of the 7th I believe. The end of the 6th could have been WW2. Although I know Tolkien stated that he didn't want his story of the Third Age being compared to it, or anything else in fact.