SHANGHAI, China - Thousands of years of Chinese linguistic heritage have come down to this: a squabble over Tom and Jerry. Dubbed into regional Chinese dialects, the warring cat and mouse have been huge TV hits - and a good way to pass home-grown culture down to the younger generation, programmers say. Not so fast, says the central government up north in Beijing, which for decades has promoted standard Mandarin as the only Chinese language worthy of the airwaves. The State Administration of Radio, Film and Television has ordered an end to broadcasting in dialect, saying kids should be raised in a "favorable linguistic environment." The move has put Tom and Jerry - or "Cat and Mouse," as the show is called here - at the center of a long-running debate about how to maintain national cohesion amid a linguistic sea of highly distinct regional accents, dialects, and wholly separate language groups. "As an artist, I think dialect should be preserved as a part of local culture," says Zhang Dingguo, deputy director of the Shanghai People's Comedy Troupe which does Tom and Jerry in Shanghainese. The government calls the Mandarin policy vital to promoting a common Chinese identity in this vast land of 1.3 billion people, 56 ethnic groups and seven main Chinese dialects spoken by the Han ethnic majority. "Thank you" is pronounced "xie xie" in Beijing, "do jey" in Hong Kong, and "sha zha" in Shanghai. Need to know a price? Ask "wa tsui gim" in Fujian, but "duoshao qian," in Mandarin-speaking northern China. Promotion of Mandarin - known here as "putonghua," or "common tongue" - began in the 1920s and became policy in 1955, six years after the communists seized power. Its use has been encouraged through an unending series of campaigns, including the current one featuring TV presenter Wang Xiaoya on billboards exhorting Shanghainese to "speak Mandarin … be a modern person." Totally distinct from Chinese, the languages of minority groups such as Tibetans, Uighurs and Mongolians are officially recognized and taught in schools. Important documents are translated into major minority tongues and four of them - Tibetan, Mongolian, Uighur and Zhuang - are on bank notes. Chinese dialects are based on the same system of writing. That means Cantonese speakers in Hong Kong can enjoy subtitled Mandarin movies and Mandarin-speakers can order off Chinese menus in the far west of the country. Use of dialects may even be strengthening in some areas with strong local identities, sometimes for economic reasons. In Guangzhou (that's Mandarin for the great southern city of Canton), broadcasters are allowed to speak Cantonese to compete with the nearby Hong Kong stations. In places like Guangzhou and Shanghai, prevalence of the local dialect helps exclude outsiders from social networks that are key to securing good jobs and entry to better schools. Outsiders say it smacks of bigotry. Despite support for dialects, Mandarin's influence reaches deep. Speaking the language well is considered a sign of good breeding and education.