This dance is called ‘Al Aardhah Al Najdyaah’. ‘Al Aardhah’ means ‘the dance’ and ‘Al Najdyah’ refers to the area of KSA called Najd which includes Riyadh and its suburbs, where King Abdulaziz the father of the Saudi Kings was born and started the unification of his Kingdom. So, in the old days when there were lots of wars led by the founder of the Kingdom and this dance was usually performed after winning a war. They usually sing “Nehmadallh Jat Aala Ma Netmanna” which means “We are grateful to Allah that we have won such a war”. After the wars ceased it became a Saudi traditional dance to be performed on occasions such as National Day and at large culture festivals such as Jenadyriah. The King will also participate in such dance as his father used to.
The drums, tassels, swords, the outfits, and all relevant decorations are derived from the old days.
(Thank you Omar for the information)