An article by Andrew Lawler discusses how archaeologists Arunima Kashyap and Steve Weber at the Washington State University determined that curries - using garlic, ginger and turmeric - were prevalent in the Indus civilization. This was done by analyzing finds from Farmana and Harappa, using starch grain analysis and other methods. Evidence for the consumption of eggplant, mango, wheat and barley was also found. These finds are apparently the earliest evidence for the consumption of ginger and turmeric in the Indus civilization.
The Slate article is at http://www.slate.com/articles/life/food/2013/01/indus_civilization_food…
An original version of the research is at http://antiquity.ac.uk/projgall/kashyap326/