Archaeologists and historians have long sought to explain the 15th-century abandonment of Angkor, with many attributing it to the 1431 invasion by Thai forces from Ayutthaya.
"The historical record is effectively blank for the 15th century at Angkor," said Dan Penny, a member of a team of Australian and Cambodian archaeologists and geographers who took part in the study published in the Proceedings of the National Academy of Sciences (PNAS).
"Angkor was never fully abandoned," Penny said, but "the elite were shifting away from Angkor," moving to new communities elsewhere with more commercial opportunities.
"This was not a collapse," Penny said. "This was in fact a decisive choice to shift focus away from Angkor."
"While the breakdown of Angkor’s hydraulic network, most likely associated with climate variability in the mid-14th and early 15th centuries, represents the end of Angkor as a viable settlement, our data indicate that it was presaged by a protracted demographic decline," the study said.
"This raises the likelihood that the urban elite did not leave Angkor because the infrastructure failed, as has been suggested, but that the infrastructure failed (or was not maintained and repaired) because the urban elites had already left."
"The absence of Angkor’s ruling elite by the end of the 14th century casts a different light over the Ayutthayan occupation of the city from 1431 CE, and over Cambodian narratives that emphasise loss at the hands of interventionist neighboring states," they added.