12- Men who have walked on the moon
11- US States that seceded from the Union
10- Ten Kingdoms of China
9- Little Rock Nine
8- Warsaw Pact countries
7- Sites of the Ancient Wonders of the World
6- Nobel Prize categories
5- Countries liberated by Simón Bolívar
4- “Big Four” leaders at post-WW1 Paris conference
3- Christopher Columbus’ ships
2- Peoples whose conflict led to the Rwandan genocide
1- Mongol emperor