No one can go a weekend in Montevideo without hearing drummers parading from roughly eight to midnight or one in the morning (ending earlier on Sundays.) The word “candombe” literally means “pertaining to blacks” in Kikongo, the Bantu language of Congo. However, in Montevideo the adjective pertains exclusively to the drums typically used and tradition of playing them thrice weekly in the streets.
The first time I saw a group on Saturday night, when the most people are out playing music, I assumed that they congregated in a set place and paraded through all of Montevideo but I found out that the happening is much more spontaneous; the groups form hanging out on the streets in each individual barrio (neighborhood). More people filter into the streets when they hear the music approaching to join in or spectate.
The night begins with some people gathering on one corner, socializing and playing the 
drums, maybe cooking some meat over a fire. The sound is a signal to come down with some wine or something to cook on the fire and say hello to your neighbors. Eventually, two corners are occupied and, before you know it, the intersection is filled with drummers and dancers who’ve arranged themselves in lines without saying a word about it. Based on how the dancers and drummers communicate (using dance and rhythm) when to stop and start moving, there appears to be an unspoken hierarchy based on experience. The dancers dance in front of the drummers, and the lead dancers dance backwards in the back of the group in order to be closer to and facing the drummers, the most experienced of whom are in front. The one or two lead dancers signal that it’s time to start or stop moving or playing and the lead drummer plays a rhythm that lets the rest of the group know. There’s few things in music more attention getting than a good, clean ending and these spontaneous musicians have it down better than many groups I’ve seen who know each other well and play together regularly.
The rhythm is always changing without ever missing a dance beat. You probably won’t notice it’s changing unless you pay close attention. Most are playing the same rhythm with some adding accents of their own. For the most part, the rhythms are in call and response format slowly morphing into different calls and different responses. Oftentimes, the entire call and response will conjugate into one call with an entirely new response. One drummer may add a radically different rhythm (meaning noticeably different in its context to the untrained ear) and no one else will join him but two repetitions after the new rhythm stops, someone will pick it up again and others will join in the second time hearing it.
Here is a clip to give an example of rhythm and the size of the group:
Candombe began when slaves of African decent gathered on Sundays and other holidays to make music together as a form of community self-help. Hundreds of years since slavery ended in Uruguay, people young and old of all different colors in every barrio drum and dance to lift their spirits.