Historical botany
Grapefruit and grapefruit were recorded in China in the 3rd ~ 4th century BC. At that time, citrus and grapefruit were planted along the Yangtze River and were both selected as tributes. However, whether the grapefruit recorded in China ancient books is the same plant as today's grapefruit has always been controversial.
Saburo Tanaka, by quoting some Japanese ancient books and Japanese folk grapefruit, concluded that the grapefruit in ancient China was an orange, not what was later commonly known as grapefruit. Yu in Japanese is homophonic with grapefruit in Chinese, and Yuzu is grapefruit in Chinese. In fact, grapefruit is grapefruit in Chinese, and Yuzu in Japanese is an orange called by the Japanese. There is a difference between the two.
Unscientific, putting the cart before the horse, because the grapefruit referred to by China people is called an orange by the Japanese because of its homonym. Sino-Japanese cultural exchange began in Qin and Han Dynasties and flourished in Han and Tang Dynasties. Grapefruit was recorded in ancient books in China before Qin and Han Dynasties (see Han Feizi and Lu Chunqiu in the 3rd century BC). That is to say, grapefruit comes before orange.