|Naadam, Opening Ceremony 2013 in Ulaanbaatar, National Sports Stadium|
From Joshua's mom...
Naadam traditionally consists of archery, wrestling, and horseback riding. The opening ceremony features parades and various demonstrations. This is a huge national holiday. It has been celebrated for centuries, but it now actually marks the nation's independence (1921) and is held July 11-13.
If you really want to read more about the festival, the government puts out a description in general: