They are one of the oldest domesticated foods with evidence showing they were eaten by humans up to 19,000 years ago. Like all of the foods in this group, lentils are a cheap source of protein. In parts of the world that have large vegetarian populations, such as India and West Asia, they are the main source of protein. When mixed with grains like rice, lentils make a nutritionally complete protein dish.
There are many varieties of lentils, with colours ranging from green to red to black. In India, lentils are used in curries called dhal and ground into a flour to make pappadums. In Ethiopia, they are made into a non-spicy yellow stew, which is one of the first solid foods Ethiopian women feed their babies.