[2] The first contacts between China and the Khmer Empire of Cambodia occurred in the Tang period, and for centuries onward the two countries shared a strong trading relationship.

Cambodia maintained relations with Ming China as early as 1421 AD during the final years of the Khmer Empire when Ponhea Yat dispatched a minister to establish formal diplomatic ties.

Also, Mao Zedong had fostered good relations with Prince Norodom Sihanouk, who also fought against Lon Nol and backed the Khmer Rouge.

[citation needed] Since 1997, China began developing closer relations with the regime of Cambodian Prime Minister Hun Sen, once a pro-Vietnamese leader and a defector from the Khmer Rouge during Vietnam's occupation of Cambodia.

[1] Facing international isolation after the 1997 coup that brought him to power, Hun Sen cultivated close ties with China, which opposed efforts by Western countries to impose economic sanctions on Cambodia.

[5]: 28 In July 2019, Cambodia was among 37 countries which signed a joint letter to the UNHRC defending China's treatment of Uyghurs and other Muslim minority groups in the Xinjiang region.

[5]: 27 During the visit of Chinese Premier Wen Jiabao between April 7-April 8, 2006 both nations signed several bilateral agreements and a treaty of "Comprehensive Partnership of Cooperation.

[1][6] China has canceled much of Cambodia's debt and granted a fresh loan of US$12.4 million for the construction of the building housing the Cambodian government's council of ministers and the restoration of the Angkor Wat temple and heritage site.

[10]: 103  In 2014, Prime Minister Hun Sen requested that China help construct a stadium for Cambodia in advance of the 2023 Southeast Asian Games.

[13]: 185  Chinese leaders expressed their appreciation for Cambodia and China's foreign minister stated, "History will prove that the Cambodian side's maintained position is correct.

[9] However, Cambodia has a significant trade deficit with China, importing over $3.9 billion (raw fabrics being the largest constituent) compared to its exports of $830 million.

According to The Cambodia Daily in 2006, Phong hill tribes in Mondulkiri province "claim that the Chinese company has colluded with the Cambodian government to illegally force them from their ancestral homeland".

[26] The Boeung Kak and Borei Keila evictions in Phnom Penh were seen by many observers as the Cambodian Government's increasing drift away from the adherence to human rights.

The Chinese funded Sesan Dam project in the northeastern part of Cambodia, threaten to lower the fish stocks, and affect the livelihood of many Khmer.