information:highlighting, structural:expansion, linguistic:paraphrasing
Agriculture

The ancient peoples of the Andes such as the Incas have practiced irrigation techniques for over 6,000 years. Because of the mountain slopes, terracing has been a common practice. Terracing, however, was only extensively employed after Incan imperial expansions to fuel their expanding realm. The potato holds a very important role as an internally-consumed staple crop. Maize was also an important crop for these people, and was used for the production of chicha, important to Andean native people. Currently, tobacco, cotton, and coffee are the main export crops. Coca, despite eradication programs in some countries, remains an important crop for legal local use in a mildly stimulating herbal tea, and illegally for the production of cocaine.