Cause: Siam Ayutthaya Dynasty was established.

1350, King Wu Tong led many people to move to the capital city of Ayutthaya, and established a powerful Ayutthaya dynasty, thus posing a great threat to the neighboring Khmer kingdom. 135 1 year, the newly established Ayutthaya dynasty launched the first war of invading Khmer, thus opening the prologue of the protracted Khmer-Siam war.

As the old hegemon of Indochina Peninsula, the Khmer at that time was always challenged by the emerging Thai country Sukhothai. Even though Sukhothai declined, Ayutthaya dynasty rose rapidly and became the most powerful new Thai dynasty in Indochina Peninsula. What's more, Ayutthaya is the closest to Angkor, the capital of Khmer.

This brought unprecedented pressure to the Khmer people, and King Nampong could not sleep well. Nampong is well aware that the Siamese's move to take Ayutthaya as its capital undoubtedly has important political and military intentions. From now on, the strength of Siam will be like a sword against the chest of Khmer. As long as the Siamese gain a foothold in Ayutthaya, the Siamese army can quickly reach the gates of Angkor at any time, thus threatening the life and death of the entire Khmer kingdom.

However, the Siam operation came faster than Nampong thought. In the second year after Siam moved its capital to Ayutthaya, the Angkor court received the news of Siam's invasion. Just as Nampong was preparing to organize troops to fight, Siam had already broken through the defense line of Khmer troops on the border between the two countries and quickly advanced towards Angkor Wat. In the face of such a crisis, Peng Lan, with a mediocre ability, suddenly felt helpless.

At this time, Sorio Thai Thai, as the deputy king of Khmer, stepped forward and took the initiative to shoulder the heavy responsibility against the Siamese army. Obviously, Mrs. Sorio is a better leader. In the face of the sudden invasion and gradual advance of the Siamese army, Mrs. Sorio did not let her panic affect her decision. He calmly analyzed that the Siamese army had gone a long way, but it didn't meet any decent resistance all the way, so the Siamese army at this time must be exhausted and underestimated.

So, based on this analysis, Mrs Sorio asked the Khmer army to stand by and get ready. When the Siamese army appeared at the gates of Angkor Wat, Mrs. Sorio personally led the army out of the city and was caught off guard by the Siamese army. Under the attack of the Khmer army, the exhausted and underestimating Siam army was quickly defeated, a large number of Siam soldiers became Khmer prisoners, and the pro-grandson of the Siam kingdom was also killed in this battle.

The victory over Siam gave Nampong great confidence, so that he had the illusion that Siam would not dare to invade Khmer easily from now on. Therefore, after this war, Nampong began to relax its guard against Siam. However, contrary to Nanbang's speculation, the defeated king of Siam, driven by a strong sense of revenge, is making more detailed preparations for the invasion.

Soon, Siam's army once crossed the Chao Phraya River, pointing directly at Angkor. Obviously, this invasion was fully valued by King Ramapo I of Siam. Under the personal leadership of King Siam, Angkor Wat was once again surrounded. This time, the Siamese army never gave the Khmer army a chance to attack suddenly. Convinced that it was difficult for him to defeat the Siamese army in the frontal battlefield, Nampong chose to stick to Angkor Wat to delay the change.

After all, Angkor is the capital of Khmer. Peng Lan believes that the capital will be besieged and the local government will send troops to rescue it. As long as they can't persist, the situation will develop in favor of Peng Lan after the arrival of the army of diligent kings from all over the country. But this time, Nanbang underestimated the strength of the Siamese army and the firm determination of the Siamese king to win.

The Siamese army, under the command of the King of Siam, not only repelled the troops from all over the country who came to the King of Qin, but also consumed the effective strength of the garrison troops. The Siamese army set up tall wooden castles outside the city and fired rockets from a distance, causing heavy casualties to the defense forces in the city. After more than a year of siege, the resistance of Angkor Wat has been severely weakened. Therefore, the Siamese army chose the east gate of Angkor Wat as the breakthrough point, forcibly broke the east gate with a heavy city-breaking hammer, and then invaded Angkor Wat.

The fall of Angkor Wat means the demise of the Khmer Kingdom. However, Siam did not occupy Angkor Wat for a long time, and members of the Khmer royal family quickly recovered Angkor Wat with the support of the Khmer people, thus restoring the overall rule of Khmer. However, the feud between Siam and Khmer did not end there.

In his later years, Siam and Khmer fell into a long-term conflict. Even decades after the fall of Angkor, Angkor was captured by the Siamese army again, and the feud between them will be entangled in the19th century.

Consequence: Bonea moved to Phnom Penh.

1434, in order to protect the security of the country and the king, Khmer King Bonea decided to abandon the old capital of Angkor, and finally chose Phnom Penh as the address of the capital of Wang Guoxin.

Conclusion: The repeated invasions of Siam brought great disasters to Khmer, and the long-term war greatly consumed the national strength of Khmer, which led to the weakening of Angkor Dynasty and gradually lost its dominant position in Indochina Peninsula.