The rainfall levels revealed that the ancient population suffered through repeated periods of severe drought during what should have been wet seasons.

“What surprised us was how clearly the seasonal cycle was recorded, it’s highly unusual to be able to access past climate information at such a high-resolution,” Daniel H. James, a postdoctoral researcher at University College London, and lead author of the research paper, tells The Art Newspaper. “

To be able to generate a sub-annual climate record that spans such a societally important time is a very rare and exciting opportunity.”The reasons for the decline of Classic Maya civilization—which happened between 800 and 1000 and is sometimes referred to as the Maya collapse—have long been debated among experts. Changing trade routes, war, civil unrest, disease and severe drought have all been cited as possible contributing factors. Now, James and his colleagues have added extra evidence for the impact of droughts.