Mexican Cuisine, like many others, is a fusion cuisine that takes elements from Mesoamerican cooking and adds a flare of European elements, especially Spanish. This is primarily a result of the Spanish conquest of the Aztec Empire.
When the Spanish arrived in Mexico they found the Aztec diet consisted primarily of corn base dishes that often featured chiles, beans, tomatoes, and herbs. But the Aztecs also frequently used chocolate, vanilla, avocado, papaya, pineapple, achiote (also known as annatto), squash, sweet potato, turkey and fish.
The Spanish introduced them to olive oil, almonds, beef, chicken and pork. The spices and herbs that are native to Mexico include chocolate (cacao), chiles and vanilla.
While they may have originated in Mexico, like many spices and herbs, their increased demand has led to their cultivation throughout the world.