Other scholars attempting to account for the rapid decline and abandonment of Angkor have hypothesized natural disasters such as disease (Bubonic Plague), earthquakes, inundations, or drastic climate changes as the relevant agents of destruction. A study of tree rings in Vietnam produced a record of early monsoons that passed through this area. From this study, we can tell that during the 14th–15th centuries monsoons were weakened and eventually followed by extreme flooding. Their inability to adapt their flooding infrastructure may have led to its eventual decline. Recent research by Australian archaeologists suggests that the decline may have been due to a shortage of water caused by the transition from the Medieval Warm Period to the Little Ice Age. LDEO dendrochronological research has established tree-ring chronologies indicating severe periods of drought across mainland Southeast Asia in the early 15th century, raising the possibility that Angkor's canals and reservoirs ran dry and ended expansion of available farmland.