I have known Ashutosh Gowariker for a long time, but the last proper conversation we had happened over a decade ago, on the sidelines of a seminar marking the 400th death anniversary of Emperor Akbar. Gowariker was then researching Jodhaa Akbar, a movie that drew extensively from the recorded history of the Mughal emperor’s life and blending that with an invented romance between him and his Rajput wife. Having witnessed how eager the filmmaker was to comprehend the historical background of the Mughal epoch, I’m sure the consultations he had with leading Indus civilisation scholars in the process of making his latest blockbuster, Mohenjo Daro, went far beyond the usual lip service. The material we have on the film so far, a trailer and some songs, give evidence of serious research. The sets simulate baked brick and streets arranged in a grid. We see bullock carts with solid wooden wheels traversing Mohenjo Daro’s wide lanes. Cotton fabrics, some dyed with indigo, are worn by the characters and sold in the marketplace.

We know so little about the era, however, that imagination had to take precedence over veracity in the film’s creation. The trailer shows the protagonist, played by Hrithik Roshan, staring at a monumental stone figure comparable in size with those commissioned by Egypt’s self-aggrandising pharaohs. It is extremely unlikely that any sculpture on that scale was produced in the Indus civilisation. The sculpted artefacts found by archaeologists are puny and of indifferent quality. Filmmakers are, of course, entitled to take liberties with facts in the service of fiction, and slant stories in a direction of their choosing. When Shekhar Kapur’s Elizabeth portrayed Catholics as sweaty fanatics or treacherous plotters and their Protestant adversaries as rational patriots, nobody in Britain or Europe cared overmuch. But history is so fiercely contested in India that Mohenjo Daro is bound to be scrutinised for the position it takes on a number of controversies, especially the crucial question: what relationship, if any, did the citizens of the Indus culture have with the Vedic people?

The teaser of the film consists of a series of "befores": Before the British Raj, before the Mughals, before Christ, before Alexander, before Buddha, there was Mohenjo Daro, it says. But all those befores take us back only 2,500 years, leaving 1,500 still blank . The way to fill that gap would be to add, "Before the Vedas", but that would invite right-wing protests and calls for a ban.

The case of the horse

In one shot from the trailer, Roshan is confronted by four rearing stallions. The placing of horses in India in 2016 BCE is bound to please ideologues on the right, for the horse causes a nearly insurmountable problem for those who insist the populations of the Indus culture spoke Sanskrit and were descended from people who composed the Rig Veda. The Rig Veda is full of horses. Horses are ridden into battle and sacrificed in great yagnas. Unfortunately, no horses appear in India’s visual and archaeological until around 2000 BC. One little sculpture from Mohenjo Daro looks a bit like a horse, but nobody can make a definitive identification because the piece is severely damaged. If the Vedic people built the cities of the Indus culture, why did they keep mentioning the horse in their hymns but never depict them alongside elephants, bulls, rhinoceros and other fauna on the beautiful stone, terracotta and metal seals they manufactured, of which over 3,500 have been found by archaeologists?

The conventional historian’s view is that the horse was first domesticated in the Eurasian Steppes between 5,000 to 6,000 years ago. Among the first people to ride the horse were speakers of Proto-Indo-European, the mother language of Sanskrit, Greek, Latin, and dozens of modern tongues. Descendants of these people spread across the continents, taking their language as well as the horse to regions from West Europe to South Asia. The exact role migration played as opposed to cultural diffusion in the spread of language and horse domestication remains an open question.

In discussing the role of the horse in Mohenjo Daro and its sister cities, we are left with two possibilities. First, that the domesticated horse was introduced to India after the peak of the Indus civilisation had passed, in which case that civilisation was not Vedic. Second, that horses and chariots existed in Harappan sites for over 1,000 years without leaving any archaeological or iconographic trace. Which seems the likelier story?

The case of Sanskrit

The language of the Vedas creates an even tougher obstacle than the issue of the horse. Two hundred and twenty years ago, on February 2, 1786, a judge and polyglot named William Jones delivered his third annual discourse in Calcutta to an organisation of learning he had founded, named the Asiatic Society. In the process, he created the discipline of comparative linguistics and the idea of an Indo-European language family. Here’s the most famous passage of the talk:

“The Sanskrit language, whatever be its antiquity, is of a wonderful structure; more perfect than the Greek, more copious than the Latin, and more exquisitely refined than either, yet bearing to both of them a stronger affinity, both in the roots of verbs and in the forms of grammar, than could possibly have been produced by accident; so strong indeed, that no philologer could examine them all three without believing them to have sprung from some common source, which, perhaps, no longer exists: there is a similar reason, though not quite so forcible, for supposing that both the Gothic and the Celtic, though blended with a very different idiom, had the same origin with the Sanskrit, and the old Persian might be added to this family.”

In the decades after Jones’ revolutionary thesis, linguists have tried to reconstruct the lost tongue from which so many of the world’s major languages have sprung, while also hypothesising about the region where that originary language was first spoken. They do this by finding words that are common to many of the descendant languages, words like father, pater and pitar/pita, which emerge from the same root. There are dozens of such words shared by Indo-European languages, one of which is the term for horse, which is áśvaḥ in Sanskrit, aspa in Old Iranian, hippos in ancient Greek, equus in Latin, and ašvà in Lithuanian (meaning "mare"). There are no common Indo-European words for elephant, camel, rhinoceros, lion, tiger, monkey, banyan and bamboo, but shared words do exist for wolf, otter, polecat, deer, rabbit, sheep, goat, pig, beech, pine, birch, and willow. Based on such evidence, linguists have made the case for a temperate homeland for the Proto-Indo-European language. Had the Indo-European family originated in India with Vedic Sanskrit, it seems likely that sub-tropical flora and fauna would form an important part of the common substrate of Indo-European words, but instead such words tend to be unique to Sanskrit and Indian languages deriving from it, and are sometimes loans from Dravidian languages. The inescapable conclusion is that the ancestor languages of Sanskrit, from Proto-Indo-European to Indo-Iranian, were spoken outside the subcontinent, and probably came to India during the declining years of the Indus Civilisation.

The case of the gods

The ancient language closest to Vedic Sanskrit is that of the Avesta, the religious text of the Zoroastrians. There are startling commonalities between the two faiths. Both the Rig Veda and the Avesta speak of a nourishing and possibly intoxicating drink that was consumed ritually. It is called soma in the Vedas, and haoma in Iranian texts.

Indian texts speak of two related groups of supernatural beings, the devas and the asuras. The former are gods while the latter usually play the role of villains. In Iran, the situation is reversed, with the ahuras being divine and the daevas nasty entities. The reversal is easily explained if one imagines a group of speakers of the Indo-Iranian parent tongue placing devas and asuras on more or less equal footing. They split up at one stage and the people who went on to compose the Avesta shifted the balance in favour of ahuras, while the composers of Vedic hymns preferred devas. If, on the other hand, one imagines Sanskrit travelling to Iran from India with the devas already defined as gods in opposition to the asuras, it isn’t easy to explain why the Iranians would then reverse the order completely.

Occam’s Razor

Occam’s Razor demands that if there are two valid explanations of a phenomenon, we ought to choose the simpler one. Not only is the Out of India thesis (the idea that Sanskrit is completely indigenous to India and the root of all Indo-European languages) incapable of explaining a number of linguistic, archaeological and iconographic issues related to the Indus civilisation and to the Indo-European language family, attempts to craft such an explanation involve incredible contortions. Why choose such convolutions when the simple explanation of the development of horse riding and of Proto-Indo-European, the entry of Sanskrit into India after 2000 BC, and the subsequent composition of Vedic hymns, satisfies observable facts?

The answer lies, of course, in Hindutva ideology. The Out of India thesis originated with Hindu nationalists such as Savarkar and Golwalkar. They needed Hinduism to be entirely indigenous in order to label Christianity and Islam inauthentic foreign imports. The left, conversely, is eager to highlight foreign origins in order to undercut the idea of one authentic national religion. Both sides play an ideological game, but in this case the left has most of the facts on its side.

Hindutvavadis attempt to hide the gaping holes in their thesis by throwing out familiar accusations of racism and imperialism, but it is unclear why imperialists would have such a fondness for the grasslands of Ukraine and Kazakhstan and the regions near the Black Sea that they would twist evidence to place the origins of horse domestication and the Indo-European language group in those lands.