The appellation of origin of the day is Mocha. Mocha is a city in Yemen, known as a market (not a grower) of coffee beans from the 15th through the 18th centuries.
A great deal of the coffee was imported from Harar in Ethiopia. A mocha latte is a chocolate-flavored coffee beverage. This article suggests that beans from Mocha tasted chocolatey and not that the city began the practice of adding chocolate to coffee.