It’s not an exclusively Chinese New Year. Japanese, Koreans, Vietnamese, Cambodians, etc. all celebrate this particular New Year.
Cambodians do celebrate “Chinese New Year” but the Khmer New Year is in mid April and lasts three days. They celebrate both, more fun. Why not?
Perhaps “The East Asian New Year” would be more appropriate.
Not Cambodians. Thailand, Cambodia, Laos, and Burma celebrate new year in the middle of April. There are sizeable Chinese minorities in these countries, and the resident Chinese will celebrate both.
This celebration takes place at the hottest time of year, just before the start of the rainy season. There is a tradition of pouring water over the hands of respected elders, which has morphed into general free-for-all water fights. In Bangkok, when I was there a couple of years, the giant super-soakers would make their appearances about ten days before.