Ancient alien crop introductions integral to Indian agriculture: an overview.
India is one of the major centers of agricultural plant biodiversity. Many of the crop plants were domesticated and a far greater number were introduced and absorbed into the country from different parts of the world since ancient times. The archaeobotanical remains and sculptural depictions and their reference in ancient literature (Sanskrit) present unambiguous evidence for introduction of 65 crop species before the 8th century. These species include crops from Americas, Africa, Near East, Central Asia, China, and Southeast Asia. The ancient introduction/occurrence of these species in India is speculated because of geological and geographical fragmentation of continental landmass followed by drift, natural or man-made transoceanic migration/movements and trade and cultural exchange. The evidence generated clears the wrong perceptions about the time of introduction of many crops such as maize, sunflower, cashew nut and others.