Hosay is the Caribbean manifestation of the Remembrance of Muharram, and was brought to the Caribbean from India in the 19th century. This, of course, is despite the virtual disappearance of Shi’a Islam from the Caribbean. Participants cut across ethnic and religious barriers, including Hindus, Christians and Muslims, Indians and Africans, etc. This is not to say that most people fully understand the original purpose of the event, evident in the festive atmosphere among most celebrants, a feature that is in continuity with the Indian versions upon which Hosay is based. In addition to Trinidad, where it is primarily celebrated, smaller celebration of Hosay also take place in Jamaica.
The floats in the pictures are tazias. The tazia (or tadjah) float represents the tomb of Imam Hussayn ibn Ali, who was killed in Karbala, Iraq on October 10, 680 AD. Drumming features prominently in Hosay celebrations - particularly the tassa, and the larger dhol. The pictures above also show two half-moons that are included in the procession. These half-moons are spun as they are paraded, and one must stay clear, because the edges are studded with blades! The red and green half-moons represent the Imams Hussayn and Hasan, his brother, respectively. The colour red signifies the blood that was spilt when Hussayn was killed, while the green represents the poison used to kill Hasan. The half-moons are only used in Trinidadian versions of Hosay.
Unlike Remembrance of Muharram events in most of the world, Hosay does not feature beating one’s chest, self-flagellation, or any other form of self-harm.
(Pictures from here, here, here, here, here, here, here.)