The history of Rum is inextricably linked to the history of colonization. Much like Cotton in North America, Sugarcane became a Cash Crop for a Triangular Trade between the colonies, Western Europe and West Africa. The resulting trade success lead to expansion of the farming across the Caribbean and South America and subsequent production of the contemporary styles of rum developed.

Sugarcane orginated in South Asia which over time had resulted in its cultivation in India. Following various historical power struggles the knowledge of sugar refinement and its alcoholic fermentation spread. Christopher Columbus brought the crop to modern day Haiti via the Spanish ruled Canary Islands along with all the required knowledge of cultivation, refinement, fermentation and distillation. 

 In French controlled Martinique Rhum Agricole is widely produced. In Brazil during the time of Portuguese rule sugar cane production moved from the island of Madeira along with the copper stills used for distillation resulting in Aguardente (fire water) and the more contemporary Cachaça. All three of these products are made from sugar cane juice. Other spirits resembling rum are made throughout this part of the world. Clairin from Haiti is a locally produced product by “craft” distilleries dotted throughout Haiti, and Charanda produced in the region of Michoacán, Mexico (which is I’m sure of no coincidence the region alongside Jalisco, famous for the production fo Tequila). Both of these products typically use cane juice and molasses in their wash. 

Molasses is a byproduct fo the refinement of sugar cane juice. The cane is stripped of the leaves (often by burning the crops), cut and transported to the milling plant where it is pressed for its juice which consists of approx 12-14% sucrose. After an initial boiling to promote sugar crystallization Grade A Molasses is produced; often sold (in the United States) as Cane Syrup. Grade B Molasses is slightly bitter and Grade C molasses is commonly referred to as Blackstrap Molasses

It is said that Rum as we know it originated in English controlled Barbados with slaves exploring the fermentation and distillation of molasses which resulted in a quite crude alcohol. Equally, in Spanish controlled Cuba the distillation of molasses was so substantial that it spurred first commercial brand of rum, Bacardi. Diamond Distillery (Demerara Distillers LTD) in Guana produce El Dorado Rum- a highly rated rum by consumers and industry alike. According to Diffords Guide, Diamond Distilleries has 13 fermenters each holding over 80,000 liters of molasses fermenting with their own unique yeast strain. The fermentation lasts 24-26 hours and results in a wash of 6.5-7%abv (see here for a detailed breakdown of abv mash). The carbon dioxide produced is funneled into the adjacent plant used for the production of Pepsi Cola for the local market- a blow back perhaps to the slave trade considering that the Kola nut (the base flavor of Cola) is indigenous to the rainforests of Africa. 

Producers will not often mention what grade of molasses is used to produce the spirit but with such a large quantity of molasses on hand at places like Diamond Distillery it is not likely that the starting ingredient is of the highest quality.  What does distinguish the final product is the stills used to produce the spirit.