The history of chocolate begins in 1900 BC, at the height of Mesoamerica (today's Mexico, Guatemala, El Salvador, Belize, as well as parts of Honduras, Nicaragua, & Northern Costa Rica). Here, the cacao seed, a gift from the God of Wisdom, Quetzalcoatl, was considered so valuable it was used as currency. Aztec citizens were required to pay tribute or 'tax' to their lords using cacao.
Native to Mesoamerica, the cacao tree fruit has been fermented as early as 1400 BC. At this time, it was prepared only as a bitter, frothy liquid drink mixed with spices & wine or corn mash. Believed to be an aphrodisiac & provide strength (Wikipedia), it was so revered that the Mayan did not consume cacao for personal use, but rather, it was exclusively consumed for either medicinal or ceremonial use. The Aztec on the other hand, would sip on it as a treat for men after banquet & included it in soldier rations.
During Christopher Columbus' 4th expedition, in the 16th Century, Europeans began to take notice of this special plant. Having witnessed the reverence paid by the Mayan, they deemed it valuable, though they didn't really 'get it'.
With the Spanish conquest the Aztec shortly thereafter, cacao was brought to Europe. Here, sugar was added to the original tonic & within a hundred years, it was popular throughout European geography & social classes. Their taste for chocolate was quite literally fed by the ever-prolific slave trade of the time. As the cacao tree was increasingly domesticated abroad, these highly labour intensive plantations, were powered by human trafficking.
Wind-fuelled & horse-drawn mills expedited the process & decreased the need for human resources, but it was the industrial revolution which truly catapulted modern production.
It was Dutch Chemist, Coenraad van Houten, in 1815, who "...introduced alkaline salts to chocolate, which reduced its bitterness. A few years thereafter, in 1828, he created a press to remove about half the natural fat (cacao butter) from chocolate liquor, which made chocolate both cheeper to produce & more consistent in quality. This innovation introduced the modern era of chocolate." In 1875, Daniel Peter invented milk chocolate by adding powdered milk, created by Henri Nestle, to the liquor.
The majority of modern cacao production takes place in Western Africa. Individual land owners, at the mercy of world market conditions, continue to this day, to cut costs through use of slave labour. Sugar is also a commodity laden in darkness & foul play making them an unfortunate pairing. Fortunately, we have access to ethically sourced cacao & sugar as consumers increasigly insist on such. Taking the time to research different companies is highly valuable not only in the sourcing process but quality as well.