Mankind’s love affair with chocolate stretches back more than five millennia. Produced from the seeds of tropical cacao trees native to the rainforests of Central and South America, chocolate was long considered the “food of the gods,” and later, a delicacy for the elite. But for most of its history, it was actually consumed as a bitter beverage rather than the sweet, edible treat it has become worldwide.

Archaeologists have discovered the earliest traces of cacao in pottery used by the ancient Mayo-Chinchipe culture 5,300 years ago in the upper Amazon region of Ecuador. Chocolate played an important political, spiritual and economic role in ancient Mesoamerican civilizations, which ground roasted cacao beans into a paste that they mixed with water, vanilla, chili peppers and other spices to brew a frothy chocolate drink.

Ancient Mesoamericans believed chocolate was an energy booster and aphrodisiac with mystical and medicinal qualities. The Mayans, who considered cacao a gift from the gods, used chocolate for sacred ceremonies and funeral offerings. Wealthy Mayans drank foaming chocolate drinks, while commoners consumed chocolate in a cold porridge-like dish.

As people of the Aztec empire spread across Mesoamerica in the 1400s, they too began to prize cacao. Since they couldn’t grow it in the dry highlands of central Mexico, they traded with the Mayans for beans, which they even used as currency. (In the 1500s, Aztecs could purchase a turkey hen or a hare for 100 beans.) By one account, the 16th-century Aztec ruler Moctezuma II drank 50 cups of chocolate a day out of a golden goblet to increase his libido.

Chocolate arrived in Europe during the 1500s, likely brought by both Spanish friars and conquistadors who had traveled to the Americas. Although the Spanish sweetened the bitter drink with cane sugar and cinnamon, one thing remained unchanged: Chocolate reigned as a delectable symbol of luxury, wealth and power—an expensive import sipped by royal lips, and affordable only to Spanish elites.

Chocolate’s popularity eventually spread to other European courts, where aristocrats consumed it as a magic elixir with health benefits. To slake their growing thirst for chocolate, European powers established colonial plantations in equatorial regions around the world to grow cacao and sugar. When diseases brought by Europeans depleted the native Mesoamerican labor pool, enslaved Africans were imported to the Americas to work on the plantations and maintain chocolate production.

Chocolate remained an aristocratic nectar until the 1828 invention of the cocoa press revolutionized its production. Attributed in varying accounts to either Dutch chemist Coenraad Johannes van Houten or his father, Casparus, the cocoa press squeezed the fatty butter from roasted cacao beans, leaving behind a dry cake that could be pulverized into a fine powder that could be mixed with liquids and other ingredients, poured into molds and solidified into edible, easily digestible chocolate. The cocoa press ushered in the modern era of chocolate by enabling it to be used as a confectionery ingredient, and the resulting drop in production costs made chocolate much more affordable.

In 1847, British chocolate company J.S. Fry & Sons created the first edible chocolate bar from cocoa butter, cocoa powder and sugar. Rival chocolatier Cadbury’s, credited with pioneering the Valentine’s Day chocolate box and chocolate Easter egg, followed suit soon after and in 1854 earned a royal warrant as purveyors of chocolate to Queen Victoria.

It was in Switzerland that chocolate production took one of its greatest leaps forward. In the 1870s, Swiss chocolatier Daniel Peter utilized powdered milk developed several years earlier by his neighbor Henri Nestlé to produce the first milk chocolate bar, and the pair eventually formed the Nestlé Company. Swiss chocolatier Rodolphe Lindt’s 1879 invention of the conching machine—which used large stone rollers to mix and aerate chocolate to give it a velvety texture and superior taste—allowed for mass production of smooth, creamy milk chocolate.

In the United States, Milton Hershey pioneered the assembly-line production of milk chocolate. After selling his caramel candy company for $1 million and producing his first milk chocolate bar in 1900, Hershey bought farmland near his birthplace in rural Pennsylvania and built an entire factory town devoted to chocolate. The grass-fed Holsteins on the surrounding dairy farms supplied the company’s milk, and a company town in Cuba supplied its sugar.

Chocolate bars soared in popularity during the Roaring Twenties. By the end of the decade, more than 40,000 different candy bars were being made in the U.S., according to Susan Benjamin, candy historian and author of Sweet as Sin: The Unwrapped Story of How Candy Became America’s Favorite Pleasure. Father-and-son duo Frank C. Mars and Forrest Mars Sr. collaborated on the idea for the Milky Way bar, which hit the market in 1923 with the chocolate for its coating supplied by Hershey’s. The family-owned business would rival Hershey’s, and Forrest Mars Sr. later partnered with the son of a Hershey’s executive to begin production of M&M candies in 1941.

H.B. Reese, who had worked as a dairy farmer and shipping foreman for Hershey’s, launched his own candy company in 1923 and five years later introduced Reese’s Peanut Butter Cups. They later came to be produced by Hershey’s—and one of the top-selling candies in the United States.

From its roots more than 5,000 years ago, chocolate has become a big business. According to research by Statista, retail sales of chocolate worldwide in 2016 totaled nearly $100 billion, including almost $25 billion in the United States alone. While the cacao plant is native to the Americas, its cultivation has now shifted to Africa, which is now the source of more than two-thirds of worldwide cocoa production.