There was a time in ancient Mexico where cacao seeds and tobacco leaves were the currency. With a superior value to other natural products, these were used in trading activities during the aztec empire.
The emperor Moctezuma would receive his tributes in cacao and at least once a day he would drink a cup of a bitter drink made with cacao seeds. Because of its strong flavor, this sacred beverage was unbearable by the spanish conquistadors.
It was after the Spanish conquest of the Aztec empire that, with the intervention of the Iberian culture, there were modifications made to mekae the bitter taste of the cacao preparation bearable. Thanks to the experiments done with milk and sweeteners, we have what we now know as chocolate.