From New York to Cape Town to Sydney, the bronze body doubles of the white men of empire—Columbus, Rhodes, Cook—have lately been pelted with feces, sprayed with graffiti, had their hands painted red. Some have been toppled. The fate of these statues—and those representing white men of a different era, in Charlottesville and elsewhere—has ignited debate about the political act of publicly memorializing historical figures responsible for atrocities. But when the statues come down, how might the atrocities themselves be publicly commemorated, rather than repressed?

In the course of her long career, the historian Lyndall Ryan has thought about little else. In the late nineties and early aughts, Ryan found herself on the front lines of what came to be known, in Australia, as the History Wars: skirmishes fought with words, source by disputed source, often in the national media. At stake was whether the evidence existed to prove—as Ryan and others had argued, and conservative historians and politicians refused to accept—that Indigenous Australians had been massacred in enormous numbers during colonization, from late in the eighteenth century to the middle of the twentieth. Even among those who grudgingly accepted that there had been widespread killings, there were still bitter, and, in some cases, ongoing, fights over the exact number of Indigenous people killed, the strength of their resistance to British settlement, and the reliability of oral versus written history. A truce has never been reached in what the Indigenous writer Alexis Wright calls Australia’s entrenched “storytelling war.” (In October, Prime Minister Malcolm Turnbull rejected the core recommendations of the government-appointed Referendum Council, which, after six months of deliberative dialogue across Aboriginal and Torres Strait Islander communities, had called for establishing an Indigenous voice to Parliament, and a process of “truth-telling about our history.”)

In 2005, in the midst of the public disputes over Australia’s history, Ryan came across the work of the French sociologist Jacques Sémelin. After the Srebrenica massacre, in 1995, there was renewed interest from European scholars in understanding massacre as a phenomenon. Sémelin defined a massacre as the indiscriminate killing of innocent, unarmed people over a limited period of time, and he characterized massacres as being carefully planned—i.e., not done in the heat of the moment or the fog of war—and deliberately shrouded in secrecy by the systematic disposal of bodies and the intimidation of witnesses. Sémelin’s typology prompted Ryan to reconsider her own earlier scholarship on the Tasmanian War, which was waged between British colonists and Aboriginal people early in the nineteenth century. This time, Ryan concluded that there were not four massacres of Indigenous people but, in fact, more than forty.

“Most historians of my generation were brought up with the idea that Aboriginal people were killed in ones or twos, similar to how settlers were killed when there’d been a dispute over stock, or women,” Ryan told me recently, at an art gallery in Sydney’s vibrant neighborhood of Kings Cross, where she was about to give a talk. Ryan, who is seventy-four, has short-cropped white hair and a slow, deliberate way of speaking that belies a very quick mind. She realized, once she’d started researching massacres, how many of her peers were still deeply in denial about the past. “People would say to me, ‘We will never know how many massacres there were, or how many Aboriginal people were killed, so what’s the point in trying to find out?’ But they would never say that about World War One or Two.”

Ryan is based at the Centre for the History of Violence at Newcastle University, up the coast from Sydney. A few years ago, she applied for a research grant to embark on a hugely ambitious undertaking: to map the site of every Australian colonial frontier massacre on an interactive Web site. Ryan defines a massacre, in this context, as the indiscriminate killing of six or more undefended people. Since Aboriginal communities tended to live together in camps of about twenty people, losing six or more people in one killing—a “fractal” massacre—usually led to the whole community collapsing.

Four years of painstaking research later, with the grant depleted, Ryan’s map is nowhere near finished. So far, it includes more than a hundred and seventy massacres of Indigenous people in eastern Australia, as well as six recorded massacres of settlers, from the period of 1788 to 1872. She estimates that there were more than five hundred massacres of Indigenous people over all, and that massacres of settlers numbered fewer than ten. (Ryan has not yet researched any massacres of Torres Strait Islander people, who are culturally distinct from mainland Aboriginal groups but share their history of colonization.) In July, Ryan and her tiny team decided it was time to release the partially completed map online. Since its launch, the site has had more than sixty thousand visitors. Contrary to Ryan’s fears, it was widely and mostly respectfully covered in the Australian media, and, at least for now, there has been no public response from conservative figures.

At the gallery in Kings Cross, the lights were turned off, and a map appeared, projected onto a large screen, showing Australia’s unmistakable outline—the continent declared by the British on their arrival to be terra nullius, land considered to belong to nobody, and thus ripe for the taking. Spread across the eastern states were dozens of yellow dots, often clustered together. Each one represented the site of a massacre of Aboriginal people.

The map’s data management still needs improvement—a consequence, in part, of limited funding, and also of Ryan’s admitted mistake in thinking she should do all the research first, before getting input from the project’s digital cartographer, Mark Brown, and digital-humanities specialist, Bill Pascoe. Even so, its power is undeniable. Ryan clicked on the yellow dot representing one of five massacres in the region of Jack Smith Lake, in eastern Victoria. On a fresh page, an aerial snapshot from ArcGIS, the geographic-information system, showed a slice of green and brown farmland and bush bordering a long, thin line of sand beside the ocean. A small square section was shaded yellow, delineating a five-kilometre radius around the site of the killings. The exact coördinates of the massacres are not identified, Ryan explained. “For many Aboriginal communities, the preference is not to pinpoint the actual site, out of respect for what is considered a taboo site of trauma. But also because sites tend to be desecrated if identified very specifically.” Some sites are on private land, or mining properties; others are at the bottom of reservoirs, because so many of the massacres happened at campsites close to creeks.

On the left of the screen was a graph, cataloguing the details of this series of massacres carried out in 1843. Aboriginal Language Group: Brataualang. Aboriginal people killed: sixty (at each of the five sites). Colonists killed: zero. Weapons used: Double-barrelled Purdey. Attacker details: twenty horsemen, known as the “Highland Brigade,” organized by Angus McMillan. In a box titled “Narrative,” these fragments form a horrific tale. McMillan, a local settler, and his group of armed horsemen, all Scots, had, for years, been attacking Aboriginal camps with impunity. In this instance, they attacked five campsites over five days. At one camp, people jumped into the waterhole but were shot as soon as they resurfaced to breathe. One of the survivors, a young boy who’d been shot in the eye, was captured by the Brigade and forced to lead them to other camps. “Human bones have been found at each of these sites on several occasions,” the text notes. “The rampage would fit the criteria of ‘genocidal massacre.’ ”

Bruised by the History Wars, Ryan set herself strict criteria for including a massacre on the map. A key signals the strength of the evidence: three stars means that there is high-quality evidence drawn from disparate sources, while one or two stars indicates that there are only one or two reliable sources, respectively, with more corroboration welcome. Most of the evidence used for the map, she told the gathering, is from contemporaneous “white people’s sources”—newspaper articles, official reports—rather than Indigenous sources, such as oral histories or social memory. (Some Aboriginal testimony is captured in those white textual sources, in the rare cases where survivors gave statements to officials or to missionaries. But Aboriginal people were for a long time prohibited from being called as witnesses in legal proceedings.) Many existing place names around the country are themselves a form of damning evidence, as the historian Ian Clark has noted in his own pioneering work on frontier massacres: Murderers Flat, Massacre Inlet, Murdering Gully, Haunted Creek, Slaughterhouse Gully.

The yellow dots on Lyndall Ryan’s map show where Indigenous people were massacred. The blue dots stand for colonists who were massacred. Map by Lyndall Ryan, Jennifer Debenham, Mark Brown & William Pascoe. Colonial Frontier Massacres in Eastern Australia 1788 – 1872, v1.2 Newcastle: University of Newcastle, 2017. This project has been funded by the Australian Research Council (ARC).

Earlier this year, Ryan presented a draft version of the map at the Australian Institute of Aboriginal and Torres Strait Islander Studies, in Canberra. The feedback was largely positive, though she was advised to use a different color for the dots than red, which is considered sacred for many communities and shouldn’t be associated only with death. As Ryan moves on to more recent massacres, she will increasingly draw on Aboriginal sources. She hopes the map will eventually be expanded to include massacres that aren’t represented in written evidence but have been known about and passed down through memory and story by descendants of victims, survivors, and perpetrators. Since the map was released, she’s heard from more than five hundred people, black and white, many from rural areas, many with details of massacres not on the map. Pascoe told me that viewers, on first seeing the map, are sometimes so overwhelmed they have to look away, but to him this is the point of mapping this kind of trauma. “People whose ancestors were involved already know what happened. But it becomes personal for everyone, because you can see what happened in a place near you, or where you grew up.”

Ryan’s decision to focus, for now, on archival research rather than community consultations was driven by funding and time constraints, but she also believes that white Australians who are skeptical about widespread frontier massacres need to be confronted with the gruesome truths recorded by their own ancestors—the magistrates and crown-lands commissioners, the settlers who wrote about killing sprees in their journals or correspondence. In the History Wars, she noted, the denialists figured out ways of discounting all evidence of massacre, no matter its provenance. “They’d say things like, well, you can’t trust evidence from a convict, they’re born liars. Same with the Native Police. Women don’t tell the truth. Soldiers who weren’t officers clearly didn’t know what was going on.” This sort of thinking would leave only sources from the two categories of whites with the most to gain from covering up massacres: the officers who gave the orders, and the male settlers who often carried them out.