When George Augustus Robinson made his way through the green and blue-black wetland near Australia’s Lake Condah in 1841, the British-born builder encountered a sight that confounded his expectations of the land and of the Gunditjmara aboriginal people who lived there.

Robinson recounted “an immense piece of ground trenched and banked,” according to a 2017 story by the Conversation. From overhead, the system of fish traps and channels Robinson saw would have looked as long and winding as the eels caught in weirs and reed-woven baskets below. The channels were lined in basalt, the black rock formed from the lava that once oozed from a dormant volcano, and had been rearranged over the years as floodplains shifted. It was an ancient aquaculture system cultivated by the Gunditjmara, who used it to trap fish and eels, grow plants, and expand their population in the region now known as southwestern Victoria. The sophisticated system was effective and ancient, with its creation dating back before Stonehenge and the Great Pyramids.

“You don’t really see it anywhere else in Australia until European agriculture,” Ben Marwick, an associate professor of archaeology for the University of Washington, told The Washington Post. “It shows us they had a high level of technical skill, understanding of physics and of the natural environment.”

Not expecting such sophistication from the aboriginal people, Robinson marveled at the structures as “resembling the work of civilized man” — though his astonishment did nothing to stop European colonizers from killing the native people and destroying parts of the area with livestock and farming.

It would be more than a century before there would be any outside appreciation for the aquaculture system.

“It was known about for a long time but ignored,” Marwick said. “It ran counter to prevailing narrative about the aboriginal people and didn’t fit the stereotype that the Europeans were more sophisticated.”

The area, which has since become known by its indigenous name, Budj Bim, was declared a UNESCO World Heritage site last year.

Budj Bim National Park was among parts of Victoria consumed by Australia’s unprecedented wildfire season, which only last week received badly needed rains to douse the blazes. The fires brought devastation to people, wildlife and natural habitat in Australia, but at the Budj Bim site, they also revealed parts of the system that hadn’t been seen for several millennia.

Denis Rose, a member of the Gunditjmara, told the Australian Broadcasting Corp. on Saturday that he wasn’t overly concerned about the fire’s impact on the ancient canal and fish trapping system. Rose, who serves as project manager for Gunditj Mirring Traditional Owners Aboriginal Corp., which preserves and perpetuates Gunditjmara culture, went to inspect the area and saw a site that would have been familiar to Robinson, the 19th-century builder.

“It was only maybe 20 meters off the track that we walk in, and it was hidden in the long grass and the bracken fern and other vegetation,” he told the ABC. The wildfires had burned off vegetation, revealing new sections of the aquaculture system. “We’ve noticed that in other parts of the lava flow as well, we’ve come across sites that just haven’t been recorded that have been very close by.”

Crews that had battled the fires since they ignited from a lightning strike around Christmas had to use low-impact techniques such as foot crews instead of rugged machinery to preserve the protected heritage site. With the fires finally subdued, a new archaeological survey is planned in partnership with the Gunditjmara.

Marwick, the professor, grew up in Australia and said Budj Bim is “one of the jewels of the crown of Australian archaeology.”

Finding new portions of the extensive aquaculture system may help researchers learn more about how the geographic environment changed over the years and more about the demographics of the ancient Gunditjmara.

“We know the population was twice the size of what we originally thought, but we might have to size up from that estimate again,” he said. Further study could also help understanding of aboriginal groups evolve.

“There’s a stereotype of an unchanging land and an unchanging people, but this shows this really isn’t the case; they appear to have continually modified the system,” Marwick said. “It’s a nice case study for the change in attitude toward aboriginal culture and how undervalued it is, especially by white Australians.”

Read more: