It is not a rare surname. I have a classmate named Yin.
The surname Yin ranks 91st in the ranking of Chinese surnames, with a population of approximately 2.28 million.
In 2013, the population with the surname Yin was more than 2.2 million, ranking 95th in the country, accounting for approximately 0.26% of the national population. Mainly concentrated in the four provinces of Shandong, Sichuan, Hunan, and Liaoning, accounting for approximately 42% of the total population with the surname Yin; followed by Hebei, Hubei, Henan, Jiangsu, and Yunnan, accounting for approximately 28%. Shandong is the largest province with the Yin surname today, and is home to 12% of the total population with the Yin surname. There are two major Yin surname gathering areas in the country: Bohai Bay and Sichuan, Hubei and Hunan.
The surname Yin is found in Shandong and Hebei, Beijing and Tianjin, Liaoning, Jilin, Heilongjiang, eastern Inner Mongolia, northern Shanxi, western end of Gansu, Yunnan, most of Sichuan and Guizhou, southeastern Chongqing, southern Hubei, Hunan, most of Jiangxi, Guangdong and Guangxi In the north, the proportion of the local population surnamed Yin is generally more than 0.27%, and in the central area it reaches more than 1%. Its coverage area accounts for about 34% of the total land area, and about 61% of the people surnamed Yin live in this area. In southern Shanxi, northern and southern Shaanxi, central Inner Mongolia, most of Henan, Hubei and Anhui, central Jiangsu, northern and southeastern Sichuan, most of Chongqing, northeastern Jiangxi, western Fujian, central Guangdong and Guangxi, northwest Guizhou, and northwest Xinjiang, the surname Yin The proportion of the local population is generally between 0.18% and 0.27%, and its coverage area accounts for about 21% of the total land area. About 27% of the people surnamed Yin live in this area.
The "Dictionary of Chinese Names" includes 107 celebrities with the surname Yin in the past, accounting for 0.24% of the total number of names, ranking tied for 88th among celebrity surnames; famous writers with the surname Yin account for 100% of the total number of famous writers in China. 0.16% of the total number of writers in the past dynasties, ranking tied for 109th; famous medical scientists named Yin accounted for 0.14% of the total number of medical scientists of the past dynasties in China, ranking tied for 107th; famous artists surnamed Yin Accounting for 0.17% of the total number of Chinese artists of all dynasties, ranking tied for 99th place.