At the quiet ruins of Harappa, one of the two main centres of an ancient civilisation that once spread from the Himalayas to Mumbai, Naveed Ahmed took in the arid hills dotted with thorn-bush. "I think the people who lived here were very different from us," said the part-time guide. "The stones and the beads [they made]; it was as if they were more sophisticated."
However peaceful this ruined city of the Indus civilisation may appear, the former residents of Harappa and the remnants of their society are today at the centre of one of the most acrimonious disputes in academia, a controversy that has allegedly led to death threats and claims of racism and cultural chauvinism.
Many experts in south Asia and elsewhere believe that symbols and marks inscribed on seals and other artefacts found here represent an as yet undeciphered language. Arguing it may be the predecessor of one of several contemporary south Asian argots, these experts say it is proof of a literate Indian society that existed more than 4,000 years ago.
But other experts based in the West say although the symbols may contain information, they are not a true language. They claim the judgement of their counterparts in south Asia may be swayed by regional nationalism.
Mohammed Hassan is curator of the museum beside the dust-blown ruins. Before leading a tour, the government official served tea and biscuits in his office and insisted the people of Harappa must have possessed a written language to store information. "If they were not literate, then how could they do so many things?" he said. "They had well-made pottery, big cities that were well-planned. They had a lot of knowledge about these things. They grew cotton, wheat, rice and barley. They traded with other cities."
The Indus civilisation covered more than 500,000 square miles and lasted, during what experts term its "mature phase", from 2,600 till 1900 BCE. The ruins, 100 miles south-west of the Pakistani city Lahore, the ruins were rediscovered in the early part of the 19th century.
The skills of its residents – at least in terms of making bricks that could endure centuries – were revealed by two British engineers, John and William Brunton, who were building the East Indian Railway Company line to connect Lahore and Karachi and needed ballast for their track. The engineers later wrote that locals told them of well-made bricks from an ancient ruined city that the villagers had made use of. With little concern for preserving the ruins, huge numbers of the Indus-era bricks were reduced to rubble and used to support the tracks heading west.
In the early 20th century, excavation of Harappa proceeded along with that of the other Indus city at Mohenjo-daro, in the south of Pakistan, and it was at that time many of the seals now on display in Mr Hassan's museum containing symbols and images of animals were discovered. And they have continued to beguile, fascinate and frustrate scientists, causing a running controversy that has played out on internet message boards, scientific papers and at academic conferences.
Like Mr Hassan, Iravatham Mahadevan, an expert in epigraphy from southern India who has been awarded the country's highest civilian award for his work, has no doubts the symbols on the Indus seals represent a genuine language. "Archaeological evidence makes it inconceivable that such a large, well-administered, and sophisticated trading society could have functioned without effective long-distance communication, which could have been provided only by writing," he wrote last year in a magazine.
"And there is absolutely no reason to presume otherwise,considering that thousands of objects, including seals, copper tablets, and pottery bear inscriptions in the same script throughout the Indus region. The script may not have been deciphered but that is no valid reason to deny its very existence."
Mr Mahadevan believes the Indus script may have been a forerunner of so-called Dravidian languages, such as Tamil, spoken today in southern India and Sri Lanka. In addition to technical clues, he says the continued existence of a Dravidian language in modern Pakistan – Brahvi, which is spoken by people in parts of Balochistan – supports his idea.
Over the years, there have been plenty of other theories both from established experts and enthusiastic amateurs. Some, with the backing of Hindu nationalists, have claimed the script may be an early Indo-European language and that remnants of it may even exist in Sanskrit, an ancient language that is the root of many present languages in north India, including Hindi. It has even been claimed the Indus script belonged to metalsmiths, and others believe it died out with the city of Harappa itself and gave rise to no successor.
Part of the problem for the experts is that, unlike for those who cracked the hieroglyphics of Egypt, there is no equivalent of the Rosetta stone, the slab of granite-like rock discovered in 1799 that contained Egyptian and Greek text. In the 1950s, academic interest in Mayan hieroglyphics intensified when experts began to study modern spoken Mayan, but for the Indus scholars there is no agreement on which, if any, modern language is the successor to their script.
In 2004, the debate was jolted into a war of words after three American scholars claimed the Indus symbols were not a language at all. In a paper provocatively subtitled The Myth of a Literate Harappan Civilisation, they said there was insufficient evidence that the symbols constituted a proper language. They pointed to various factors: that there was no single long piece of text; that there was disagreement over the number of actual symbols and that other well-organised societies had been illiterate. The symbols, they argued, may well contain information in the same way that an image of a knife and fork together might represent a roadside eatery but they were not a language that could record speech.
The ensuing uproar came mainly from south Asians. One of the American scholars, Steve Farmer claimed people would approach him in tears after he gave talks and that he had even had death threats. Comments on internet discussion boards accuse him and his colleagues of trying to prove that "non-Western cultures were less advanced". Mr Farmer, who lives in California, said he believed much of the anger was driven by those wishing to promote pet theories about Dravidians, indigenous Aryan Hindus or "the general man in the street who wants to think ancient India was of the same order as Egypt or Mesopotamia. It's total rubbish". He added: "I have never seen anything like the passion that there is in India. There is not that sort of passion in the Middle East about ancient things."
More recently, the Indus controversy has been joined by a team of Indian scientists who ran computer programmes which led them to conclude the symbols almost certainly constitute a language. Central to their claims, published last year in Science, was the theory of "conditional entropy", or the measure of randomness in any sequence. Because of linguistic rules – such as in English the letter Q is almost always followed by a U – in natural languages the degree of randomness is less than in artificial languages.
One of the authors, Rajesh Rao, who was born in Hyderabad but is now based at the University of Washington, became fascinated by the Indus culture after studying it at school. His team measured the randomness with which the individual Indus symbols appeared on seals and compared that to the randomness of several natural and artificial languages. Mr Rao said it was closest to a natural language. "The Indus civilisation was larger than the ancient Egyptian, Chinese, and Mesopotamian civilisations and the most advanced in terms of urban planning and trade," he said. "Yet we know little about their leaders, their beliefs, their way of life, and the way their society was organised. Many of us hope that decoding the script will provide a new voice to the Indus people."
Yet as soon as Mr Rao's team published its findings, Mr Farmer and his colleagues hit back, denouncing their conclusions and methodology. Mr Rao, whose team has since issued a detailed defence of their theory, said he was surprised at the level of contention, within south Asia and beyond, but also at some of the comments he claims Mr Farmer's group levelled at him.
So whether the Indus is a script with hidden meanings may never be deciphered. Naveed Ahmed, a 24-year-old part-time guide, whose family has lived "forever" in a village on the edge of the ruins speaks Punjabi, an Indo-Aryan language from the same family as Sanskrit. Was it possible a linguistic thread connected the language he used with what had been spoken - and possibly written – by the people who once occupied the ruined city? "I don't know if it is the same," he said. "But it's a possibility that our language came from them. It is always a possibility."