Julia Wallace para The New York Times
SIEM REAP, Camboya, 19 de septiembre.- Durante décadas, los arqueólogos mantuvieron sus ojos en el suelo de este lugar, a través de la espesa selva, arrozales y campos de pastoreo de búfalos, verde esmeralda y suave con el barro durante la temporada del monzón.
Se pasaron toda su carrera tratando de encontrar montículos o depresiones en la tierra que les permitiera mapear incluso pequeñas partes de Angkor, el centro urbano en el corazón del imperio Khmer, que cubría una vasta región de lo que hoy es Camboya, Tailandia, Vietnam y Laos desde aproximadamente el año 802 a 1431. En los tiempos modernos, poca evidencia material existía más allá de una red de templos monumentales de piedra, incluyendo el famoso Angkor Wat, y los asentamientos en expansión que, presumiblemente se desplegaban en abanico alrededor de los templos desde hace mucho tiempo tragados por la selva.
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| Monje en Angkor, centro urbano del Imperio Khmer. (Billy H.C. Kwok para The New York Times) |
Pero a principios de este año, los arqueólogos Shaun Mackey y Kong Leaksmy, armados con un dispositivo GPS portátil que contiene los datos de un reconocimiento aéreo de la zona que está cambiando la forma en que se estudió Angkor,llegaron directamente a un campo lleno de terrones y plagado de marcas de tractores. Se veía a simple vista como un parche de tierra ordinaria, pero los datos aéreos habían identificado como un sitio de interés un muro de contención de un montículo donde los antepasados de los camboyanos de hoy podrían haber alterado el paisaje para construir casas.
Casi inmediatamente después de pisar el campo, Mackey, con los ojos clavados en el suelo, descubrió un fragmento de cerámica celadón. Pronto el equipo había aparecido un pequeño tesoro de tiestos y comenzó a tomar notas.
"No es atractivo, como un templo, pero para un arqueólogo que es muy interesante que tengamos esta representación de la actividad cultural", dijo. Él y Kong Leaksmy son parte de un consorcio de investigadores denominado Iniciativa de Camboya Arqueológica Lidar (CALI), acrónimo de Light Detection and Ranging o Laser Imaging Detection and Ranging, que utiliza una tecnología conocida como lidar para disparar impulsos ultrarrápidos de luz en el suelo, desde el láser montados en helicópteros. La forma en que rebotan puede mostrar la presencia de gradaciones sutiles en el paisaje, lo que indica los lugares donde las civilizaciones del pasado alteraron su entorno, aunque enterrado debajo de una espesa vegetación u otros obstáculos.
Con voz suave, tocado con un sombrero fedora, Mackey, un veterano de 14 años de trabajo de campo, señaló que antes de la disponibilidad del lidar, una investigación en busca de elementos arqueológicos en el paisaje de Camboya implicaba años o incluso décadas de trabajo.
"Pasamos horas clavándonos espinos, entre bambúes y densos matorrales y arbustos, con la esperanza de que encontrar algo", dijo Mackey.
Los helicópteros de CALI volaron durante 86 horas en marzo y abril de 2015 sobre más de 1,910 kilometros cuadrados, o 737 millas cuadradas, con monjes budistas que bendicen los sensores lidar antes del despegue. Los datos generados durante los vuelos, sobre la base de unos 40 mil millones de mediciones individuales, ahora están siendo verificados y se harán públicas.
Damian Evans, el arqueólogo que encabeza la iniciativa, dijo: "La vegetación oscurece estas partes de Angkor y otros sitios monumentales. El lidar nos permitió ver a través de la vegetación ".
Los secretos de un Imperio
El resultado, dijo el Dr. Evans, ha sido una nueva comprensión sin precedentes del cómo se veía el imperio Khmer en la cúspide de su poder, con los mapas generados por lidar revelando un paisaje urbano complejo que se extiende por varias provincias de Camboya hoy en día, junto con una sofisticada red de canales, terraplenes y diques que los Angkorias utiliza para controlar el flujo del agua.
"Es bastante sorprendente", dijo. "Cuanto mayores son los templos, mayor la infraestructura urbana que lo rodea es probable que sea mayor, por lo que no se perdieron, en el sentido de que supone que deben estar allí. Pero, por supuesto, es una cosa totalmente diferente ser capaz de verlos en detalle increíble y cómo funciona y cómo funcionaba, cómo evolucionó la morfología de estos lugares."
El grupo ahora está utilizando los mapas para hacer excursiones más específicas en el campo, "verificando en el terreno" los datos lidar, para asegurar que sean exactos, y excavando para determinar dónde podrían ser útiles. En una misión reciente, Mackey inspeccionó una carretera recién pavimentada en una camioneta conducida por Kong Leaksmy.
Although the Khmer empire’s great stone monuments have endured for centuries, spawning a $60-million-a-year tourism industry and preserving information about the dynasty of god-kings who ordered their construction, the stuff of everyday life at Angkor, made from wood, mud, thatch and brick, has long since rotted away in the hot and humid climate. Almost nothing has been known about the lives of those who built the temples and served its rulers — who they were, how they lived, what they believed.
David Chandler, a professor emeritus at Monash University in Melbourne, Australia, and a leading historian of Cambodia, said the new lidar data was particularly exciting because it was providing more information than ever about how ordinary people lived in the Khmer empire.
Historians had assumed that the residents of Angkor existed — “these temples certainly didn’t get built by themselves,” Dr. Chandler said — and they had cobbled together some understanding of the area’s population through inscriptions, notes from a Chinese diplomat who visited Angkor, and a few other sparse clues. Dr. Chandler compares the process to trying to understand American history from a small collection of obituaries and Fourth of July speeches.
But with lidar-made maps, people who had spent their lives trying to retrace Angkorian history could actually see for the first time an intricate network of houses, gridded streets, canals, bridges and even mud-and-brick palaces.
“People imagined it was a city, but they didn’t know how to imagine it, because they didn’t know what it looked like, Dr. Chandler said. “Now they do.”
“This is where Angkorian research is going to go from now on: research into the people who built the temples, not the people whom it was built for,” he added. “It’s putting the population of the city back in view.”
The Greater Angkor Project, a team from the University of Sydney in Australia, has been trying since 2010 to identify and excavate ancient mounds believed to have been households in the Angkor Wat compound. When the team started its research, it spent months simply trying to identify where all the mounds were. But after it received preliminary lidar data in 2012, it realized immediately that the mounds were arranged in a tight grid pattern, indicating houses lined along roads, as in a modern city.
“Lidar made everything new and exciting,” said Heng Phipal, a Cambodian archaeologist who worked with the project.
David Chandler, a professor emeritus at Monash University in Melbourne, Australia, and a leading historian of Cambodia, said the new lidar data was particularly exciting because it was providing more information than ever about how ordinary people lived in the Khmer empire.
Historians had assumed that the residents of Angkor existed — “these temples certainly didn’t get built by themselves,” Dr. Chandler said — and they had cobbled together some understanding of the area’s population through inscriptions, notes from a Chinese diplomat who visited Angkor, and a few other sparse clues. Dr. Chandler compares the process to trying to understand American history from a small collection of obituaries and Fourth of July speeches.
But with lidar-made maps, people who had spent their lives trying to retrace Angkorian history could actually see for the first time an intricate network of houses, gridded streets, canals, bridges and even mud-and-brick palaces.
“People imagined it was a city, but they didn’t know how to imagine it, because they didn’t know what it looked like, Dr. Chandler said. “Now they do.”
“This is where Angkorian research is going to go from now on: research into the people who built the temples, not the people whom it was built for,” he added. “It’s putting the population of the city back in view.”
The Greater Angkor Project, a team from the University of Sydney in Australia, has been trying since 2010 to identify and excavate ancient mounds believed to have been households in the Angkor Wat compound. When the team started its research, it spent months simply trying to identify where all the mounds were. But after it received preliminary lidar data in 2012, it realized immediately that the mounds were arranged in a tight grid pattern, indicating houses lined along roads, as in a modern city.
“Lidar made everything new and exciting,” said Heng Phipal, a Cambodian archaeologist who worked with the project.
Unearthing Ordinary Life
Since then, members of the project have used lidar to target areas for deeper excavation, unearthing sandstone from the temples that might have been recycled into floors for city dwellers, and analyzing a garbage dump on the Angkor Wat grounds full of burned food remains and broken ceramics. They have found some of the first evidence of what Angkorians ate (rice and pomelo fruit) and how they cooked (in earth pots over fires). And they have come to understand that the gridlike pattern inside Angkor is just part of a much larger urban agglomeration, challenging conventional wisdom that the temple cities were discrete and self-contained.
“Previous maps only show us different temples — they look like different units, where settlements around them seem to be concentrated around these temples — but with lidar we know that is not actually the case,” Mr. Heng Philpal said. “We know it was all inhabited, and the city is larger than expected.”
Being able to see the true scope of the city has led to discoveries in other areas, too. Lidar has helped find the giant quarry field where most of the sandstone to build the temples was taken from, and has identified mysterious earthen spirals close to Angkor Wat and a few other temples that might have served aesthetic or religious purposes.
At a remote but massive temple called Preah Khan of Kompong Svay, which the Khmer king Jayavarman VII used as a base to raise an army against invaders from the east, scholars had worked for over a decade to determine what lay below the surface, with little success. They ultimately concluded that the area was not thickly settled. But the lidar data revealed a dense cityscape that even included the same spirals seen at Angkor Wat, and helped pinpoint areas for archaeologists to dig that had not been looted.
In other cases, what lidar has not found is just as revealing. At the temple Banteay Chhmar, on the Thai border, archaeologists had also struggled to find evidence of settlement. The lidar data confirmed this, leading Dr. Evans to conclude that it was not the center of a city but perhaps a temple or a garrison that saw only waves of temporary settlement.
Perhaps most crucially, the long-held narrative of the collapse of Angkor is being recast by lidar evidence. Based on stone inscriptions in the temples, scholars have long believed that the empire fell in 1431 after its capital was sacked by an invading Thai army, and that the population of the city moved closer to Phnom Penh, Cambodia’s current capital.
But when these areas were scanned, there was no evidence of an influx of refugees. This suggests that while there might have been a political schism in 1431 that induced members of the royal family to move closer to Phnom Penh, the vast majority of people stayed near Angkor and only gradually moved away.
This understanding is unfolding day by day as the research continues. At Site 305, for example, Mr. Mackey and Ms. Kong Leaksmy uncovered bits of water jars, showing that the area included households, and shards of blue-and-white Chinese tradeware dating from after the 1400s.
“This helps feed into the concept that Angkor wasn’t really abandoned,” Mr. Mackey said.
“When myth becomes such entrenched history, archaeology is a way of challenging the written record, particularly because history is often written by the powerful who give voice to their own agendas,” he said. “But the material remains.”
To Ms. Kong Leaksmy, a recent university graduate who used lidar data to write her thesis on a small temple called Banteay Sra, the takeaway was simpler.
“I can see many, many points that I cannot see just by eye,” she said of the new tool. “It’s amazing for me.”
Since then, members of the project have used lidar to target areas for deeper excavation, unearthing sandstone from the temples that might have been recycled into floors for city dwellers, and analyzing a garbage dump on the Angkor Wat grounds full of burned food remains and broken ceramics. They have found some of the first evidence of what Angkorians ate (rice and pomelo fruit) and how they cooked (in earth pots over fires). And they have come to understand that the gridlike pattern inside Angkor is just part of a much larger urban agglomeration, challenging conventional wisdom that the temple cities were discrete and self-contained.
“Previous maps only show us different temples — they look like different units, where settlements around them seem to be concentrated around these temples — but with lidar we know that is not actually the case,” Mr. Heng Philpal said. “We know it was all inhabited, and the city is larger than expected.”
Being able to see the true scope of the city has led to discoveries in other areas, too. Lidar has helped find the giant quarry field where most of the sandstone to build the temples was taken from, and has identified mysterious earthen spirals close to Angkor Wat and a few other temples that might have served aesthetic or religious purposes.
At a remote but massive temple called Preah Khan of Kompong Svay, which the Khmer king Jayavarman VII used as a base to raise an army against invaders from the east, scholars had worked for over a decade to determine what lay below the surface, with little success. They ultimately concluded that the area was not thickly settled. But the lidar data revealed a dense cityscape that even included the same spirals seen at Angkor Wat, and helped pinpoint areas for archaeologists to dig that had not been looted.
In other cases, what lidar has not found is just as revealing. At the temple Banteay Chhmar, on the Thai border, archaeologists had also struggled to find evidence of settlement. The lidar data confirmed this, leading Dr. Evans to conclude that it was not the center of a city but perhaps a temple or a garrison that saw only waves of temporary settlement.
Perhaps most crucially, the long-held narrative of the collapse of Angkor is being recast by lidar evidence. Based on stone inscriptions in the temples, scholars have long believed that the empire fell in 1431 after its capital was sacked by an invading Thai army, and that the population of the city moved closer to Phnom Penh, Cambodia’s current capital.
But when these areas were scanned, there was no evidence of an influx of refugees. This suggests that while there might have been a political schism in 1431 that induced members of the royal family to move closer to Phnom Penh, the vast majority of people stayed near Angkor and only gradually moved away.
This understanding is unfolding day by day as the research continues. At Site 305, for example, Mr. Mackey and Ms. Kong Leaksmy uncovered bits of water jars, showing that the area included households, and shards of blue-and-white Chinese tradeware dating from after the 1400s.
“This helps feed into the concept that Angkor wasn’t really abandoned,” Mr. Mackey said.
“When myth becomes such entrenched history, archaeology is a way of challenging the written record, particularly because history is often written by the powerful who give voice to their own agendas,” he said. “But the material remains.”
To Ms. Kong Leaksmy, a recent university graduate who used lidar data to write her thesis on a small temple called Banteay Sra, the takeaway was simpler.
“I can see many, many points that I cannot see just by eye,” she said of the new tool. “It’s amazing for me.”
