Although I find the name of this festival quite offensive, this is what it's called in Salalah whether I like it or not. The festival, otherwise known as "Mahrajan Al Zunooj" is a gathering of all former black slaves and their families to perform dances and displays of loyalty for His Majesty. The date is this event is never known in advance. An order comes from the palace, Oman TV is informed to come record it, it's never on TV but as far as I know is recorded for the party mentioned above. The event I believe starts with a visit to a grave, followed by rituals, following by this gathering of thousands of people. They all wear purple indigo wraps and go crazy for a couple of hours.
Today the festival took place (as usual, on a random date at a moment's notice. I was privileged enough to be able to go and enjoy it up close. The history of this event is ambiguous and even creepy (hint: involvement of djinn? magic?). I don't have time at the moment to post photos but I'm re-posting photos from 2012. Same exact scene. Enjoy!