I liked the article, but it's mistaken in its use of named centuries. It says "In the 12th century, the Mongol ruler Genghis Khan consolidated the largest empire in human history", but instead means the 1200s, which is the 13th century. (Recall the years 1-99 are the first century though the year numbers don't start in the 100s.) This mistake happens a few times in the article, but at least its consistent.