Exactly a hundred years ago began the journey that led to the discovery of Mohenjodaro in Larkana district in Sind, now in Pakistan. That journey took off in Calcutta. The olden story was unravelling at a talk organised at the Indian Museum in Calcutta in June. The speaker, Phanikanta Mishra, used to be director of the Eastern Circle of the Archaeological Survey of India (ASI).

Mishra's narrative turned around Rakhaldas Banerji, who was also with the ASI. Not too many people remember Rakhaldas, not even within the ASI. His centenary in 1985 passed unmarked, as did his 125th year of birth. There is only one photograph of him, commonly available - it shows an unremarkable Indian in Western wear, hair parted in the middle and a Chaplinesque moustache.

Mishra continued. The year 1917 turned out to be a lucky one for Rakhaldas. To begin with, there was the promotion. Rakhaldas, who was at the time assistant superintendent of the ASI and in-charge of the archaeological section at Calcutta's Indian Museum, was made superintendent of the Western Circle. It was a big deal. The Western Circle was, after all, the largest circle and comprised Bombay, Sind, Hyderabad and central India. Rakhaldas moved to Pune to assume his new charge.

Mishra's talk is long but not long enough. His book on Rakhaldas is yet to be published. Is there anyone who can tell us more? Mishra claims Rakhaldas's granddaughters live in Calcutta but won't talk. "They are furious with the ASI for wronging Rakhaldas," he says and clams up on specifics.

A book on Rakhaldas by Banaras Hindu University (BHU) scholar Yama Pande was written in the late 1980s and published in 2016. Pande died in 1991 but her detailed research helps The Telegraph piece together the Mohenjodaro discovery puzzle.

Rakhaldas had joined ASI as an excavation assistant in 1910. It was an open secret that he was the blue-eyed employee of Sir John Marshall, director-general of the ASI, though no one could deny the fact that he was a very learned man - scholar, epigraphist and numismatist.

"Rakhaldas started very young," says Gautam Sengupta of Visva Bharati's department of Ancient Indian History, Culture and Archaeology. The former director-general of the ASI talks about the legend's many-splendoured contributions: his books Bangalar Itihasa or The History of Bengal and Prachin Mudra or Ancient Coins; the coin catalogue for the Bangiya Sahitya Parishad, a literary society in Calcutta; and a book on the eastern Indian medieval school of sculpture. In her book Monuments, Objects, Histories, Tapati Guha-Thakurta, professor of History at the Centre for the Study of Social Sciences in Calcutta, writes: "The whole venture of 'scientific' history writing that Rakhaldas and his contemporaries spearheaded in those years was premised on the centrality of the datable artefact and its reliability as an evidence for history... allowing it [the study of the past] to break free of its dependence on mythological or literary texts."

Rakhaldas also wrote historical novels - nine - in Bengali. "They gave him the chance to go beyond limits imposed by archaeology and articulate his own perception of the past," says Sengupta. Commenting on one titled Pashaner Katha, Guha-Thakurta says: "It is a scholar's novel and the way he uses his archaeological knowledge to turn a dead monument into a living history of a people is amazing." The novel is an autobiography of Bharhut Stupa of Satna, Madhya Pradesh. The stupa is now housed at the Indian Museum.

He was also a nationalist. His early novels are mostly set in the pre-Muslim period when the Pala and Sena dynasties (8th to 12th centuries) ruled the eastern part of the Indian subcontinent. This period, according to him, represented "Bengali civilisation" at its heights.

So a picture emerges of Rakhaldas as a scientific man, obsessed with dates, proud of his culture and looking for ways to acknowledge that culture beyond the British framework within which he operated in his professional capacity. He was a man of independent thought, brought up in privilege. His father's family had been in the service of the Nawab of Bengal, while his mother's side served the ruling family of Cooch Behar. This was not a man who was going to unquestioningly accept the superiority of the British.

The situation was ripe for a clash.

As boss of the Western Circle, in 1920, Rakhaldas came upon some mounds in the dry beds of the Indus river. And this while he was looking for Greek victory pillars. "The reason he was looking for Greek pillars was that Marshall wanted him to find relics from the Gandhara period (1st to 5th century) to prove J.T. Wheeler's thesis that Indian civilisation learned from the Graeco-Roman one," says Sengupta. The British notion was that Indians were incapable of reaching the standards in classical architecture and sculpture that they did just by themselves.

The first round of excavations revealed a Buddhist stupa belonging to the Kusana period (2nd and 3rd centuries). As the area around the stupa was dug up, the archaeological team came upon microliths (tiny flints, part of a bigger tool) and pieces of pottery that did not match anything found earlier. Further excavations revealed a 5,000-year-old civilisation only a few feet below the Buddhist structure.

Former director of the Indian Museum Shyamal Chakrabarty has a story about the discovery of Mohenjodaro. It goes: Rakhaldas was feeling the inside of an earthen vessel found while excavating the stupa. He was checking for cracks, when he cut his finger on something. On close inspection, it turned out to be a microlith or flint. More such microliths were found at the site.

Rakhaldas knew his proto-historic objects. Proto-history refers to the time before recorded history of a culture begins. The microliths helped him join the dots. The dots that put him on the Mohenjodaro trail.

At the time, Pandit Daya Ram Sahni was excavating Harappa. Rakhaldas figured out the connection between the two places.

The discovery of Mohenjodaro immediately put Indian civilisation in the same league as the Egyptian and Mesopotamian ones, the world's oldest. Without it, the British would never have accepted that Indian civilisation pre-dated theirs.

Immediately after his "discovery", Rakhaldas submitted an internal report to Marshall. It didn't get published but the news that an ancient Indian civilisation had been found was splashed in the Illustrated London News in 1924. The discovery was credited to Sir John Marshall.

Yama Pande writes how Rakhaldas wanted to continue excavations at Mohenjodaro but funds dried up, as did his luck. The next thing we know, a series of incidents took him farther and farther away from Mohenjodaro. First, he was diagnosed with diabetes and had to take a few months off. Then, he was transferred back to the Eastern Circle for medical treatment. But that was all logistics.

Intellectually, Rakhaldas continued to be preoccupied with Mohenjodaro. In 1926, he submitted a detailed report to Marshall.

In Rakhalcharit, Rakhaldas's biography published in the Bangiya Sahitya Parishad magazine, Suniti Kumar Chatterjee writes that when Marshall did not acknowledge the report, Rakhaldas wrote to him saying: "These people [the ASI] will not allow me to publish anything on Mohenjodaro but you can. I am sending you my findings, conclusions and photographs..." The article was eventually published in a Bengali periodical, possibly without the knowledge of the ASI.

Soon after, Rakhaldas sought permission to visit the Chausath Yogini temple in Bhedaghat near Jabalpur to check some inscriptions. Ten days after his visit in October 1925, the temple mahant lodged an FIR against him. Reason cited: removal of a statue from the site. An arrest warrant was issued in his name, writes historian and friend Ramesh Chandra Majumdar in the foreword to the second edition of Bangalar Itihasa.

Eventually, the case was dismissed and the departmental enquiry found the charges against him unsupported. Marshall, however, made it clear that Rakhaldas should resign.

So far as the Marshall-Rakhaldas equation is concerned, different people have different takes. Shyamal Chakraborty holds that Marshall was genuinely fond of Rakhaldas and supported him. "Only when the student became greater than the teacher did the odd jealousy reveal itself."

Jayanta Sengupta, director of the Indian Museum, says this credit-taking was routine behaviour. "In those days Indians did not get any credit, be it Radhanath Sikdar [mathematician and surveyor who first calculated the height of Mount Everest] or Rakhaldas Banerji. The Indians did the legwork and the sahibs took all the credit."

After his dismissal, Rakhaldas, who had a lavish lifestyle, found himself short of funds. According to Majumdar, he was generous to a fault, loved good food, employed a Portuguese chef, maintained two phaetons and a bunch of friends. His admirers jumped to his rescue, says Guha-Thakurta. The Maharaja of Mayurbhanj commissioned him to write a history of Odisha, Sir Asutosh Mukherjee offered him a job in Calcutta University, claims the varsity website. Educationist and politician Madan Mohan Malaviya invited Rakhaldas to head the department of Ancient Indian History And Culture at the newly-founded BHU.

Rakhaldas joined BHU in 1928. Two years later, at 45, he succumbed to diabetes-related complications.

Shyamal Chakrabarty reveals that in January 1930, Rakhaldas received a letter from the then director-general of the ASI, H. Hargreaves. The letter came along with a 166-page typewritten document - the article on Mohenjodaro that Rakhaldas had sent Marshall four years ago. The letter read: "Sir John thinks it could be unkind to not let you know that many of your theories are quite untenable and your statements incorrect." Hargreaves also urged Rakhaldas to get his "report" printed before the book by Marshall was out so "there are no misunderstandings". The photographs, he informed, had gone missing.

The book, Mohenjodaro and the Indus Civilisation, edited by Sir John Marshall was published in 1931. In the foreword, Marshall mentions Rakhaldas's name as something he "can't pass over in silence" and says "to him belongs the credit of having discovered if not Mohenjodaro itself, at any rate its high antiquity".