The decline of the Khmer Empire, centered around the awe-inspiring Angkor Wat in present-day Cambodia, wasn't a sudden event, but rather a gradual culmination of several factors:

• Environmental challenges: Scholars believe changes in the region's climate might have played a role, with reduced rainfall impacting the vast hydraulic network that sustained Angkor's agriculture and population.
• Internal pressures: The empire's expansion placed considerable strain on its resources and administration. Succession struggles and rebellions weakened central authority, making it harder to maintain control over far-flung territories.
• Shifting political landscape: Rising kingdoms like Ayutthaya in Siam (modern-day Thailand) and Dai Viet (Vietnam) posed growing threats to Khmer dominance. External conflicts and raids destabilized the empire's borders.
• Economic decline: The complex hydraulic system required extensive maintenance, and its potential inefficiency due to silt build-up could have hampered agricultural productivity and revenue. Additionally, trade routes shifted, diminishing the economic importance of Angkor.
• Religious shift: While Hinduism had been the state religion, the rise of Theravada Buddhism gradually shifted religious focus away from the devaraja cult, potentially undermining the justification for centralized monarchical power and the immense construction projects associated with it.

The year 1431 is often cited as the symbolic end of the Khmer Empire when Ayutthaya sacked Angkor. However, the decline was a gradual process, with the empire fragmenting and losing territory over decades. Even after 1431, pockets of Khmer civilization persisted, and its cultural influence endured in Cambodia and beyond.