Sinosphere
The Sinosphere, also known as the East Asian cultural sphere, or the Sinic world, encompasses multiple countries in East Asia and Southeast Asia that historically were heavily influenced by Chinese culture, norms and traditions. According to academic consensus, the Sinosphere comprises four entities: Greater China, Japan, Korea, and Vietnam. Other definitions may include Mongolia and Singapore, largely due to limited historical Chinese influences or increasing modern-day Chinese diaspora. The Sinosphere is not to be confused with Sinophone, which indicates countries where a Chinese-speaking population is dominant.
https://en.wikipedia.org/wiki/Sinosphere