It was in the late 1930s that the Rastafarians began to gain a significant presence in Kingston, and by this time the pre-Rasta Burru peoples (a culture of people in rural Jamaica who were known for their drumming rituals a century ago) had fully settled in the slums.
Unlike the scenario in America, drumming in the Jamaican plantation system was officially tolerated, and the Burru-men, in addition to their role as timekeepers for slave labor, were keepers of African sound. In their search for “anciency” and cultural roots, the Rastafari knelt at the feet of the Burrus, appropriated their looks, style, and musics and, in return, imparted to them a political theology of race. But what was most important to this union of the Burrus and the early Rastafari were the rituals of sound that both communities instituted in the colonial ghettos of Kingston.
Saakana has traced the Burru drumming ritual back to a Ghanaian ceremony that took place around Christmastime. In the 1930s, the ritual of drumming was a customary way of welcoming discharged prisoners back into the folds of the ghetto community.

When the Rastafarians took over the ritual, they modified it, adding their own thematic obsessions to the African songs of insult and praise. From this came the ritual of the nyabinghi, which was said to mean “death to black and white oppressors” and became a term also used to describe the most orthodox members of the Rastafarian creed. In the sacred space of ritual, members of the faith meditated, reasoned with each other, debated Old Testament doctrine, and soundly criticized the exploitative and racist system they were living in. And they beat the drums, chanting down Babylon and conjuring up an alternate space of black community called “Africa.“

They did this in the yards of West Kingston, the same spaces that decades later would provide the genesis of the Jamaican sound systems.

Found in Bass History from 

The Sound of Culture: Dread Discourse and Jamaican Sound Systems by LOUIS CHUDE-SOKEI 

(Language, Rhythm, and Sound: Black Popular Cultures into the Twenty-first Century, 1997)