Kang Youwei, according to existing data, it was Kang Youwei who first proposed "New China".
Strictly speaking, ancient "China" is an adjective, not a proper noun. Of course, "China" in history is not the same as the scope of "China" today. None of the dynasties in ancient my country used "China" as the official name of the country. The country name of the Han Dynasty is "Han", the country name of the Tang Dynasty is "Tang", the country names of the dynasties established later include Song, Liao, Jin, Yuan, Ming, etc. The names of the countries signed in the treaties signed by the Qing government and foreign countries are "Qing Dynasty".
Until the founding of the Republic of China in 1912, China was not officially synonymous with our dynasty. After the Ming Dynasty, some places began to be called China. It was mainly foreigners and Westerners who came to China. They liked to call China China. We know that the word China can be called China, but it can also be translated as Central Empire, Central Dynasty. China is so good. So in the future, when the Qing Dynasty came, they sometimes called China China in the West, and we ourselves also called China .
It was not until the Revolution of 1911 that "China" was used as the abbreviation of "Republic of China". After liberation, we also used "China" as the abbreviation of "The People's Republic of China". Now, there is only one "China" in the world, which is the Republic of China.