The catastrophic event that caused massive flooding in China in 1931 was the Yangtze River Flood. This disaster, one of the deadliest natural calamities in recorded history, resulted from a combination of heavy rainfall and snowmelt, overwhelming the riverbanks. An estimated 1 to 4 million people lost their lives due to the floods, which destroyed homes, farmland, and infrastructure. Additionally, millions were displaced and faced food shortages, leading to a humanitarian crisis. The flooding significantly influenced Chinese society and politics, affecting land reform and water management policies in the subsequent years.