Dead men usually tell no tales; but a 4000 year old skeleton from Balathal, Rajasthan (40 km north east of Udaipur) has revealed some fascinating tales.
This skeleton, of a man who probably was 35+/-10 years and 5’10”, was found in a settlement which flourished from 3700 – 1820 BCE; the people there had pottery and copper and cultivated barley as well as wheat. He was buried between 2500 – 2000 BCE — much before the decline of the Harappan civilization — and was a leper. In fact, this skeleton is the oldest example of leprosy in the world.
But he was not Harappan: he belonged to the Ahar-Banas culture. In the Mewar region of Rajasthan, hunter-gatherers developed farming communities in the middle of the fifth millennium BCE, independent of the Harappan culture. By around 2500 BCE, they became prosperous and had fortified settlements, roads, and lanes. Also, the earliest burned brick (4000 BCE) was found in Gilund at this site^[2].
By 2500 BCE, Ahars had trade relations with the Harappans to the north. They also had trade relations with their contemporaries in South and Central India and the skeleton confirms it. This skeleton was buried with vitrified ash from cow dung. So far the Southern Neolithic ash mounds found in South Deccan and North Dharwar were believed to be cattle settlements or the result of  cow dung disposal. Now we can speculate that they were the result of funeral activities of a shared tradition.
Besides this domestic connection, these people had international contacts as well. There are two strains of leprosy: an Asian one and an East African one. It is possible that the African one was transmitted to Asia around 40,000 BCE or vice versa at a much later date. The second one seems to have happened since lerosy depends on human contact and it must been transmitted over the trading network involving the Ahars, Harappans,people of Magan, Mesopotamians and Egyptians.
This skeleton fits well with  the Atharva Veda (Hymn 23, 24) making it the earliest historical reference to leprosy. The Ebers papyrus, dated to 1550 BCE has been interpreted to contain evidence of leprosy, but the earliest affected skeleton found in Egypt has been dated only to 400 – 250 BCE.
Another point is regarding the burial; after 2000 BCE, burial was uncommon except for some special cases like infants and spiritual people. Harappan skeletons were both cremated — there is evidence at Sanauli at least — and buried, but true burials are very few compared to expected numbers. Many archaeologists believe that cremation must have been widely practised by Harappans. Also, at Dholavira and other sites, dozens of graves turned out to be without any bones which implies symbolic burials.
It is believed that the burial at Balathal followed the Vedic tradition: lepers were buried alive in some parts of India. Also there is evidence that diseased bodies were sometimes not cremated.
Two other skeletons were also obtained from Balathal, but of a later date^[3]. They were found in the padmasana or samadhi posture — a striking evidence of yoga practice and burial of people perhaps regards as spiritually advanced. Even now in India, spiritually advanced people are not cremated, but buried.

(One of the skeletons from Balathal in samadhi posture)

Also:

The excavations reveal a large number of bull figurines indicating the Ahar people worshipped the bull ^[6]. At Marmi, a site near Chittorgarh, these figures have been found in abundance indicating it could be a regional shrine of the bull cult of this rural population. Discovery of cow-like figurines in Ojiyana, the first site found on the slope of a hill, has baffled archaeologists. Cow-worship was not a known Ahar practice. “There are no humps and we can see small teats,” B.R.Meena, superintendent, ASI Jaipur circle, who undertook the excavation, says, “These are certainly cows.” Other archaeologists suspect them to be bull calves but insist if further studies prove these to be cows, one could infer that the cow was a revered animal and the Hindu practice of treating the cow as a holy animal can thus be of pre-Aryan antiquity. [Were they cow worshippers?]

Vedic burial, skeletons in samadhi posture, cow worship in a civilization contemporary with Harappa —- does this imply that the Ahar-Banas were Vedic people or Ahar culture was adopted by later Vedic culture or Ahars adopted it from an earlier Vedic culture?
The large number of bull figurines found at Ahar and Gilund could indicate a bull cult^[6]. There is a debate over if the figurines represent bulls or cows, but these figurines were part of the second phase of the Ahar culture (2100 – 1800 BCE) or as late as 1600 BCE ^[7] and are the only clue to the religious beliefs of the Ahars^[8].
Another clue is the time frame of these skeletons. While the leper was dated to 2000 BCE, the skeletons in samadhi were from700 BCE^[9]. So while the leper burial was unusual, there is nothing unusual about burying a man in samadhi posture by the Early Historical Period.
While the bull figurines and the skeletons in samadhi were known earlier, this leper skeleton has added new information about this less known culture. Hopefully as more papers come out, we will get a clear picture on their religious beliefs, such as if this Vedic burial was an exception or a common practice.
Notes:

1. This post is based on [4]. Many thanks to Michel Danino for information and images of the samadhi skeletons and Harappan burials. Also thanks to Gwen Robbins, the primary author of [2, 4], for patiently answering many questions.

Reference:

1. The Indus Civilization: A Contemporary Perspective by Gregory L. Possehl
2. A panel on the The Cultural Diversity of Northwestern South Asia at the time of the Indus Civilization convened by Prof. Gregory Possehl (University of Pennsylvania) and Prof. Vasant Shinde: Deccan College
3. Gwen Robbins, Veena Mushrif, V.N. Misra, R.K. Mohanty and V.S. Shinde, Human Skeletal Remains from Balathal: a Full Report and Inventory, Man and Environment, XXXII(2) 2007, pp. 1-25.
4. Ancient Skeletal Evidence for Leprosy in India (2000 B.C.), Gwen Robbins et al.
5. Piecing the Ahar Puzzle by Rohit Parihar
6. Encyclopedia of Prehistory: South and Southwest Asia By Peter Neal Peregrine
7. Tribal roots of Hinduism By Shiv Kumar Tiwari
8. The Rise of Civilization in India and Pakistan by Bridget Allchin
9. The skeletons have also been dated all way back to 1800 BCE