3 ideas
Chilli, potato, tomato, maize, cashew, pineapple, papaya and groundnut came to India only after about 1500, through Portuguese and later colonial trade from the Americas. Before chilli arrived, black pepper, long pepper and ginger supplied pungency, so a dish that now defines a regional cuisine may be less than five centuries old. Achaya uses this to separate a cuisine's felt antiquity from its documented history.
Achaya reconstructs what people ate by lining up several independent kinds of evidence. These include charred grains and seeds from archaeological digs, food words and their spread across languages, prescriptions in religious and medical texts, and the accounts of foreign travellers. When these sources agree, a date or origin becomes credible. Loanwords are especially useful because they show the direction in which a food moved, such as Sanskrit or Dravidian names spreading outward with the crops they describe.
In Indian eating customs, food carries purity or pollution, and this governs who may cook it, who may eat it with whom, and from whose hands it may be accepted. Food cooked in water (kachcha) was treated as more easily polluted than food fried in ghee (pakka), so rules for sharing across social groups depended on the cooking medium. Rules about dining together therefore enforced social hierarchy through everyday meals.