 Complete the following phrase:  Although the countries share no common border, China has had a historic cultural and commercial relationship with Cambodia. The 950,000 Chinese in Cambodia constitute 3-5 of Cambodias population, and although they were discriminated against by the Khmer Rouge and the Vietnamese, they have re-emerged as a prominent business community. Cambodia first made contact with 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. China has used Cambodia as a counterweight to the dominating influence of Vietnam. In the mid-20th century, Communist China supported the Maoist Khmer Rouge against Lon Nols regime during the Cambodian Civil War and then its takeover of Cambodia in 1975. Also, Mao Zedong had fostered good relations with Prince Norodom Sihanouk, who also fought against Lon Nol and backed the Khmer Rouge. When Vietnamese military invaded Cambodia in 1978, China provided extensive political and military support for the Khmer Rouge. In 1979, the Chinese Peoples Liberation Army waged a 