The history of chocolate dates back over 5,000 years. The cacao tree is native to the tropics of the Americas. The cocoa bean was first domesticated at least 5,300 years ago in what is present-day southeast Ecuador by the Mayo-Chinchipe culture, before being introduced in Mesoamerica. Originally prepared as a drink, chocolate was served as a bitter liquid, mixed with spices or corn puree. In Mesoamerica, it was believed to be an aphrodisiac and to give the drinker strength. Today, such drinks are also known as "Chilate" and are made by locals in the south of Mexico and the north triangle of Central America. After its arrival to Europe in the sixteenth century, sugar was added to it and it became popular throughout society, first among the ruling classes and then among the common people. In the 20th century, chocolate was considered essential in the rations of United States soldiers during war.