Mexico is a country of rich culinary history, with food making up an important part of its culture and traditions. Its cuisine reflects not just the diverse landscape and the countless crops produced there, but its links to cultures which span back thousands of years. Authentic Mexican food is believed to have originated from the Mayan Indians, nomadic hunters whose diets mainly included wild game, tropical fruits and beans. Salsa made from an early kind of tomato was first sold in Aztec market places, as were avocados and cashews, while enchiladas have also been linked to the Aztecs. Cocoa was also highly prized in the Aztec Empire, where it was used by the upper classes to make a thick chocolate drink, as well as being used as a currency. There is archaeological evidence that chilli peppers were in use since 5000 BC, but in the 1300s chillies found their way into staple diets, along with honey and salt. Meanwhile, the Spanish invasion of 1521 saw the introduction of dairy products, garlic, wheat and livestock such as sheep, pigs and cows - as well the start of Mexican crops such as coca, tomatoes and chillies making their way to Europe.