Yams do not seem to be anywhere in Indian cuisine.
The staple of the diet in Nigeria is the infamous yam and the indigenous various soups. India's staple is predominantly rice, with wheat being a very important staple in particular parts of the country. Just as yams are incorporated into almost every dish in Nigeria, rice is used during every meal. Rice is found in Nigeria, but not in mass quantities and in only three different forms--plain white rice, jollof rice and fried rice. India is home to more then two hundred (200) varieties of rice (Rice).
Although rice is the staple of India's diet, it's all-important' only in the south, and the best Indian rice, Basmati, is found in the north. Basmati is a long-grained, fragrant rice cultivated mainly in the Himalayan foothills. This rice is different then many other types because it actually improves with age. It can be kept up to 10 years given the right environment. Actually, the older it is the fluffier and less sticky it is when cooked (Ehler).
Another type of rice found in India is Patna. Also grown in north India, this long-grained rice has a relatively mild, yet pleasant, taste (Alden). While Basmati rice is used on special occasions, Patna rice is eaten on a daily basis. It is relatively inexpensive, so it can also be ground into flour. Red Patna is a short-grained, red-husked rice grown in central and west India and coastal regions. It is usually consumed locally because it is quickly and lightly boiled after harvesting in order to shorten its cooking time. This rice is nutty', chewy and very nutritious (Alden).
Finally, Ambemohar is a round-grained rice that's not usually available outside India. It's used in dishes where a fragrant rice such as Basamati would also be suitable. While not considered as high a cuisine as Basmati rice, it's pleasant tasting and considerably cheaper. It is also used for making flour.
Rice is considered a religious food in India and has been woven into the country's cultural mystique.