The Mystery of the Indus Valley Script: An Ancient Puzzle Yet to Be Solved

A fish under a roof, a headless stick figure, and a series of lines resembling a garden rake—these are among the many symbols forming an ancient script that has confounded scholars for centuries. Despite the script belonging to an advanced civilization that thrived thousands of years ago, its meaning remains elusive, igniting intense debates, threats against researchers, and even substantial monetary rewards for anyone who can crack the code.

The most recent offer came last month when the chief minister of an Indian state announced a $1 million prize for decoding the script of the Indus Valley civilization. This ancient society, which once spanned present-day Pakistan and northern India, holds critical historical significance.

“A really important question about the pre-history of South Asia could potentially be settled if we are able to completely decipher the script,” said Rajesh P. N. Rao, a computer science professor at the University of Washington who has spent over a decade studying the script.

Deciphering the script could unveil insights into a Bronze Age civilization believed to have been as advanced as ancient Egypt and Mesopotamia. Scholars estimate that this civilization may have housed millions of people and developed impressive urban planning, standardized measurements, and extensive trade networks.

More importantly, understanding the script could help answer deeply contested questions about the ancestry of the Indus Valley people and their modern descendants—an issue intertwined with the politically charged debate over India’s indigenous heritage.

“Whichever group is trying to claim that civilization would get to claim that they were among the first to have urban planning, this amazing trade, and they were navigating seas to do global trade,” Rao explained.

“It has a lot of cachet if you can claim that, ‘Those were our people who were doing that.’”

Why Has the Script Remained Indecipherable?

Although the script remains a mystery despite being documented as early as 1875, archaeological excavations of key Indus Valley sites, such as Mohenjo-daro in Pakistan’s Sindh province, have provided valuable insights into the civilization itself.

The cities were constructed in grid patterns, similar to modern-day New York or Barcelona, and had well-planned drainage and water management systems—features described in one research paper as “unparalleled in history.”

During the second and third millennia BCE, Indus merchants engaged in extensive trade across the Persian Gulf and the Middle East. They transported goods such as copper ingots, pearls, spices, and ivory. The civilization also produced fine gold and silver jewelry and established settlements far beyond its core region.

However, around 1800 BCE—more than a millennium before the rise of ancient Rome—the civilization declined, leading its people to migrate to smaller villages. Some scholars attribute this collapse to climate change, citing evidence of prolonged droughts, shifting temperatures, and unpredictable rainfall that may have crippled agriculture.

Despite these discoveries, our knowledge of the Indus civilization remains limited compared to contemporaneous societies like ancient Egypt, Mesopotamia, or the Maya. The primary reason for this gap is the undeciphered script, which appears on artifacts such as pottery and stone seals.

Several factors contribute to the difficulty in decoding the script. First, there are relatively few examples to study—only about 4,000 inscriptions have been found, compared to the estimated five million words of ancient Egyptian text available in various scripts, including hieroglyphics.

Additionally, most Indus inscriptions are quite brief, often appearing on small stone seals measuring just one square inch, with sequences typically containing only four or five symbols.

Crucially, no bilingual artifact has been discovered containing both the Indus script and its translation into another known language. In contrast, the Rosetta Stone was instrumental in deciphering Egyptian hieroglyphics because it included the same text in Greek and Demotic script. Furthermore, unlike Egyptian or Mesopotamian records, there are no known names of Indus rulers that could serve as reference points for translation, as Cleopatra and Ptolemy did for ancient Egyptian.

Nonetheless, experts have reached some general conclusions. Most agree the script was written from right to left and was likely used for both religious and economic purposes, such as marking trade goods. Some symbols even have widely accepted interpretations, such as a headless stick figure representing a person.

However, without a breakthrough akin to the Rosetta Stone, these remain hypotheses. “No unanimity has been reached even on the basic issues,” noted Indus scholars Jagat Pati Joshi and Asko Parpola in a 1987 book cataloging hundreds of seals and inscriptions.

Even decades later, the mystery persists. “Not a single sign is deciphered yet,” said Nisha Yadav, a researcher at the Tata Institute of Fundamental Research in Mumbai, who has worked with Rao and studied the script for nearly 20 years.

The Controversy Surrounding the Script’s Origins

For many, solving the Indus script isn’tjust about academic curiosity—it carries significant implications for understanding ancient migration patterns and cultural identity.

There are two primary theories about the script’s linguistic roots. One group argues that the script is linked to Indo-European languages, including ancient Sanskrit, which gave rise to many modern languages spoken across northern India.

Most scholars believe Indo-European languages were introduced to India by Aryan migrants from Central Asia. However, some proponents claim the reverse: that Sanskrit originated within the Indus Valley civilization and later spread toward Europe.

According to Rao, their argument is: “Everything was within India to begin with … Nothing came from outside.”

The second major theory suggests that the Indus script is connected to the Dravidian language family, still spoken primarily in South India. If true, this would indicate that Dravidian languages were dominant in the region before the arrival of Aryan languages in the north.

1. K. Stalin, the chief minister of Tamil Nadu who announced the $1 million reward, subscribes to this belief, which Rao describes as the more “traditional” theory—though both perspectives have reputable scholars supporting them.

Meanwhile, some experts reject the debate altogether, arguing that the distinction between Aryan and Dravidian identities is not as clear-cut as many assume.

“There are no Dravidian people or Aryan people—just like both Pakistanis and Indians are racially very similar,” said Indus scholar Iravatham Mahadevan in a 1998 interview.

“We are both the product of a very long period of intermarriage, there have been migrations … You cannot now racially segregate any element of the Indian population.”

Despite these discussions, the issue remains sensitive. In a 2011 TED Talk, Rao mentioned receiving hate mail after publishing his findings. Other researchers, including Steve Farmer, have even received death threats. Farmer and his colleagues sparked controversy in 2004 by arguing that the Indus script was not a written language at all but merely a set of symbolic markings, similar to modern traffic signs.

Efforts to Crack the Code

Despite the tensions surrounding the script’s meaning, many scholars and enthusiasts remain captivated by the challenge.

Some, like Parpola—one of the leading experts in the field—have attempted to decipher the meanings of individual signs. He suggests that, in many Dravidian languages, the words for “fish” and “star” are homophones. Since stars often symbolized deities in other ancient scripts, he theorizes that Indus symbols resembling fish may represent gods.

Others, such as Rao and Yadav, focus on identifying patterns within the script. Using computer models, they analyze sequences of signs, removing certain symbols and seeing if the computer can predict the missing ones.

This approach helps researchers understand grammatical structures—much like how the letter “Q” in English is almost always followed by “U.” It also aids in reconstructing inscriptions with missing or damaged sections.

Interestingly, seals found in West Asia contain Indus symbols but follow different patterns, suggesting the script may have adapted to multiple languages, much like the Latin alphabet.

Meanwhile, the $1 million prize has reignited public interest. Rao noted, “I used to get about one or two emails a week. But now, after the prize was sent out, I pretty much get emails every day,” with messages coming from people worldwide, even families working on the puzzle together.

Ultimately, decoding the script may require global collaboration, substantial funding, and diplomatic efforts to access disputed archaeological sites.

Yet, for Yadav, the pursuit itself is rewarding. “If we decipher the script, it will open a window into the lives and ideology of Indus people,” she said.

“These details are just hiding from us today … That keeps me glued to the problem rather than anything else.”