Aqellal...

Well this is a type of folklore that belongs to the south of Morocco towards the south of the now world famous city of Ouarzazate. It consists of rythmic chants along with just the beat of the Moroccan drum and a traditional instrument called "Deff", a kind of closed drum which is covered with goat skin that you can beat from both sides (although here we can only see those who are beating regular drums - other seated drumers are using the more specific "Deff").
The group consists roughly of ten or twelve beaters who sing back to the voice of the main singer, usually an old man seated in the middle (but whom we can see here standing next to the middle drumer - not so old though). He is the one who takes the leads and goes on changing tunes as the song procedes. He instructs the other members to the rises and falls and to the danses they execute in group.