Latest / The Khmer Empire: The Lost Civilization Behind Angkor Wat — Fexingo History / The Sandstone That Built Angkor: Khmer Quarrymen and the Mountain of Phnom Kulen
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- Lucas: So, we've talked a lot about the temples — Angkor Wat, the Bayon, Banteay Srei — but we haven't really looked at what they're made of. I mean physically, the stone itself. Luna: Sandstone, right? I've heard that mentioned. Lucas: Exactly. But not just any sandstone — it came from a specific mountain about forty kilometres northeast of Angkor: Phnom Kulen. That mountain was sacred long before the Khmer Empire. It's where Jayavarman II declared himself a chakravartin, a universal monarch, in 802 CE, and where the cult of the devaraja, the god-king, was established. But it was also the empire's primary quarry for centuries. Luna: So they were hauling sandstone from a holy mountain to build even holier temples. Lucas: Exactly. And the scale is staggering. Angkor Wat alone required roughly five million tons of sandstone. That's about a million blocks, each weighing anywhere from two hundred kilos to over a ton. And they didn't have wheeled vehicles or iron tools — at least not in the early periods. They used wooden sledges and rollers, and they moved these blocks overland and down the Siem Reap River in the rainy season, when the water level was high enough to float barges. Luna: How do we know they came from Phnom Kulen specifically? Lucas: Geologists have matched the mineral composition of the sandstone in the temples to samples from the quarries on Phnom Kulen. But we also have direct archaeological evidence — there are dozens of quarry sites on the mountain where blocks were partially cut and then abandoned. Some still have the chisel marks and the wedge slots visible. And there's a really interesting feature: at one quarry, you can see where a block split along a natural fracture line and they just left it, maybe because it cracked wrong. Luna: So how did they actually cut the stone without metal? I know the Khmer had iron, but I've read that early on they might have used something else. Lucas: Good question. For the fine carving — the bas-reliefs and the lintels — they used iron chisels, definitely. But for the initial quarrying, the splitting of massive blocks from the bedrock, they likely used a technique called fire-setting. You heat the rock with a fire, then douse it with water, and the thermal shock creates cracks. Then you drive wooden wedges into the cracks and soak them — the wood expands and the block splits. There's actually a famous experiment from the 1930s by the French archaeologist Henri Marchal, who recreated this on Phnom Kulen and proved it worked on that specific sandstone. Luna: So it's not just brute force — it's clever use of materials. Lucas: Right. And it meant that the quarries were seasonal. You'd have to do the quarrying in the dry season, because fire-setting doesn't work well in the rain. Then when the monsoon came, the rivers rose, and you floated the blocks downstream. The whole operation was probably timed to the calendar. The court would commission a temple, and the king's officials would send word to the quarry master on Phnom Kulen, who would oversee a workforce that could number in the thousands. They weren't slaves, by the way — most evidence suggests they were corvée labour, which means they owed a certain number of days of work to the state, like a tax paid in labour. Luna: Did the quarrymen live on the mountain permanently? Lucas: Some probably did, at least during the quarrying season. There are remains of temporary shelters near the quarries — post holes and hearths. But the mountain was also a religious site, so there were permanent temples and monasteries there too. The most famous is the riverbed of a thousand lingas — a stretch of the river where the bedrock is carved with hundreds of small stone lingas, the phallic symbols of Shiva. So the whole mountain was saturated with meaning. The stone itself was sacred, and using it in a temple was a way of bringing that sanctity into the heart of the capital. Luna: I want to ask about the scale for different kings. Like, did Suryavarman II use the same quarry as Jayavarman VII? Lucas: Mostly yes, but there were variations. The sandstone at Banteay Srei — which is from the late tenth century, under Jayavarman V — is a particularly fine-grained pink sandstone that came from a specific quarry on Phnom Kulen. It's a different colour from the greyish sandstone used at Angkor Wat. And for the later temples under Jayavarman VII, like Ta Prohm and Preah Khan, they also used a kind of laterite for the foundations and walls, but sandstone for the visible surfaces and the carvings. So the quarrying industry was active for at least four hundred years. Luna: Was there any environmental impact? I mean, removing that much stone from a mountain must have changed the landscape. Lucas: It definitely did. The quarries are like huge scars on the mountain — some are ten metres deep. But the Khmer also reforested parts of it, because the mountain was considered a sacred forest. There's a Chinese account from the thirteenth century — Zhou Daguan, who visited Angkor around 1296 — and he describes Phnom Kulen as a place of dense jungle with stone quarries that were still active. He mentions that the king at the time, Indravarman III, had recently built a temple there. So the quarrying continued even as the empire was declining. Luna: Did they ever quarry out the entire mountain? Could you see it from Angkor? Lucas: You can't see Phnom Kulen from Angkor — it's too far and the terrain is flat in between. But the mountain is about 480 metres high, so it's a landmark in the region. And the quarries are mostly on the southern slope, which faces Angkor. So the blocks came down that side. There's a particular site called the 'quarry of the large blocks' where you can see a block that was estimated to weigh about forty tons — and it was never moved. It's just sitting there, partially cut, with wedges still in place. It gives you a sense of the ambition and also the limits of their technology. Luna: What about the unfinished statues? I've heard of those on Phnom Kulen. Lucas: Oh, yes — the so-called 'Phnom Kulen Brahmas'. They're four huge figures, about two metres tall, carved directly into the bedrock on the mountain. They're unfinished — you can see the rough outlines, the faces only partially carved, and the stone still attached to the ground. They were probably meant to be detached and moved to a temple, but for some reason the work stopped. Maybe the king died, or the project was abandoned for political reasons. They're haunting, really — they look like they're emerging from the stone, half-born. Luna: So the mountain still holds all these clues. It's like a museum of the building process. Lucas: Exactly. And it's a fragile one. The quarries are now a protected archaeological zone, but they're also threatened by looting and by the encroachment of rubber plantations. The APSARA Authority, which manages Angkor, and the French School of Asian Studies — the EFEO — have been surveying and mapping the quarries with LIDAR and GPS. They've identified more than fifty quarry sites on Phnom Kulen. Some are just small pits, others are massive open-faced cuts. And they're finding tool marks, inscriptions, even small shrines where workers might have worshipped before starting a job. Luna: Inscriptions — can we read them? Lucas: Some are just names, maybe of the quarry master or the overseer. Others are short dedications. There's one that reads, in Old Khmer, something like 'May the work be completed without accident'. So there's a human dimension here. These were real people, sweating and straining, and they left their mark in more ways than one. Luna: I'm wondering about the economics. How did the state organise all this? Was there a department of quarries? Lucas: There must have been. We know from temple inscriptions that the Khmer state had a complex bureaucracy. For example, the Sdok Kak Thom inscription, which we've mentioned before, lists officials for various royal works. There were probably 'masters of the stone' — a term that appears in later inscriptions. And the quarries were likely under the authority of a high-ranking official, maybe even a member of the royal family. The stone was, after all, a strategic resource. Without it, you couldn't build the temples that legitimised the king's rule. Luna: So controlling the quarry was controlling the means of cosmic legitimacy. Lucas: Exactly. And that's why Phnom Kulen was so important. It wasn't just a convenient source of stone — it was the sacred mountain where the empire had begun. Jayavarman II had performed the ritual that made him a god-king on that very mountain. So by using its stone, each subsequent king was connecting himself to that founding moment. It's the same reason why later kings built their temples on the site of earlier ones — you're tapping into the accumulated power of the land. Luna: That gives a whole new layer to the phrase 'sacred mountain'. Lucas: It really does. And you know, the way we talk about these temples often focuses on the finished product — the soaring towers, the serene faces. But behind all that was an immense, grinding physical effort. The stone had to be found, cut, moved, shaped, carved, and polished. And it took generations. The men who quarried the stone for Angkor Wat probably never saw it finished. Their sons and grandsons saw it completed. And that kind of intergenerational project — that's what built the Khmer Empire. Luna: It's almost like those unfinished statues on Phnom Kulen are a metaphor for the whole enterprise. Lucas: Yeah, I think that's a beautiful way to put it. They're frozen in time, still waiting for the final touch. And in a way, that's how we experience the Khmer Empire today — through its unfinished stories, its broken stones, its gaps. But even in that state, it's awe-inspiring. Luna: Speaking of the gap between the grand vision and the human effort — we should mention something. This show is entirely ad-free, and that's a choice we make so we can spend time on the details that matter, like the quarrymen of Phnom Kulen. If you appreciate that approach and want to support it, you can find us at buy me a coffee dot com slash fexingo. No pressure, just an option for those who find value in what we do. Lucas: Thanks for that, Luna. And yeah, it's precisely that kind of listener support that lets us dive into the gritty, human side of history — the stuff that doesn't make it into the glossy documentaries. So, back to the mountain: one last thing I want to mention is that Phnom Kulen is also where the Khmer Rouge had their final stronghold in the 1990s. There are still landmines in some areas, which makes archaeological work there dangerous. But the teams are slowly clearing it. So the mountain has been a site of power, of creation, and of violence, across a thousand years. Luna: It's like a palimpsest — every era writes its own layer on the same stone. Lucas: Exactly. And the stone itself is the thread that ties it all together. From the lingas carved in the riverbed to the blocks that became Angkor Wat, to the bunkers of the twentieth century — it's all the same sandstone, formed millions of years ago under a shallow sea, then raised up, and then reshaped by human hands. Luna: I'll never look at an Angkor temple the same way again. Lucas: That's the goal. Next time you see a picture of Angkor Wat, think of the man who split that block on the mountain, the elephant that dragged it to the river, and the boatman who guided it downstream. They're all part of the story.