Ethnic groups in India

According to some people, India is not a country but a continent. Everything seems to be diverse here. For instance, there are several hundred different mother tongues in India, out of which 29 languages are spoken by more than a million and 122 by more than 10,000. But more interestingly, I started to notice different ethnicities.

We found a friendly spa in our neighborhood that we loved to go to once in a while. Most of the employees there look more oriental than Indian. Some look Thai and some look Mongolian. I asked them where they were from, expecting them to say that they were from either Burma or Thailand, but most of them were from the state called Manipur (later I found out that Manipur was the scene of fierce battles between Japanese soldiers allied forces during the WWII...). Ignorantly, I said "so.... you are INDIAN!". They laughed and told me that yes they were Indians, but they also told me that the culture, food, and almost everything differs from what people know of as "India". For instance, they told me they eat lots of pork there :)

I got interested in the ethnicity of Indians and started to do some research, but there seem to be lots of "theories" but nothing conclusive yet. One article said it is divided into six major ethnic groups: 1) Negrito, 2) Proto - Australoids or Austrics, 3) Mongoloids, 4) Dravidian, 5) Western Brachycephals, and 6) Nordic or Indo-Aryans.
Negrito is considered to be the earliest to have come to India from Africa. The Jarawas or the Great Andamanese are some of the examples. They tend to have broader heads. Their hill tribes can be found in south India.
Proto - Australoids or Austrics were the next to come to India and said to be the ones who built the foundation of Indian civilization. They are characterized by their wavy hair, medium height, dark complexion, long heads and flat nose.

Mongoloids are the ones that I recognized at the spa I go to. They are found in northeastern parts of India such as Assam, Nagaland, Mizoram, Meghalaya, Arunachal Pradesh, Manipur, and Tripura. They have a lighter complexion, oblique eyes, high cheekbones, and are of medium height. 

Dravidians are the peoples of South India. According to the wiki, it refers to the diverse groups of people who natively speak languages belonging to the Dravidian language family. They are mostly found in South India, Sri Lanka, Bangladesh and Pakistan. They are said to be shorter in height and darker in complexion. 

Western Brachycephals are Alpinoids, Dinarics, and Armenoids. Parsis and Kodavas falls under this category as well. Although the particular article said they were broad headed, but they also seem Caucasians (maybe broad headed Caucasians) according to the wiki article.

Indo-Aryans were the last one to immigrate to India around 2000 to 1500 B.C. (still a long time ago...).  They mostly lived in the northern and central part of India. However, according to the wiki, this term rather refers to the wide collection of people united as native speakers of the Indo-Aryan branch of the Indo-Iranian family of Indo-European languages (wow!) and that most of them live in South Asia.
I also found this interesting article, and according to this, there is no race such as Dravidians or Aryans and that the Indians are categorized as Caucasians (btw, Caucasians are not equal to "white" people). And, also the wiki about Indo-Aryans also said this: "Several recent studies of the distribution of alleles on the Y chromosome, microsatellite DNA, and mitochondrial DNA in India have cast strong doubt for a biological Dravidian "race" distinct from non-Dravidians in the Indian subcontinent. A 2009 study of 132 individuals using 560,000 SNPs concluded that the modern Indian population is a varying admixture of two divergent ancient populations, the Ancestral South Indians (60,000 ya) and the Ancestral North Indians (40,000 ya)."