Here is an extremely similar question from two days ago that has an excellent answer by u/alricofgar. However your comparison of the 5th to 15th century is a pretty huge gap making any comparisons difficult. The 15th century is much closer to today than to the 400s. A better comparison would be to the Roman empire that preceded it, or to another country that wasn't affected by the "dark ages", as that term really only applies to western Europe and mostly to the British Isles in specific.