The song "The East is Red" is a Chinese song that became well-known during the Cultural Revolution in the 1960s. During this time period, it was considered to be the de facto national anthem of the country.
The main reason why the Communist Party wanted to popularize this song was to increase legitimacy and support for their cause. The lyrics celebrate Mao Zedong, and create an image of him that is idealistic and heroic. This allowed him to develop a personality cult around his person.