First, at that time, people described the monkey as "A San". All foreigners looked like monkeys in the eyes of China people, especially Indians. Because of their sense of superiority, they thought they were higher than India, so they disdained Indians to be called "A San".
Secondly, it is said that because of colonial relations, Indians have to know English as civil servants, but because they know English, they also like to put on airs in front of China people. Usually, when they are not fluent in Chinese, they will unconsciously add "I said ..." (I said ...) Because my pronunciation is very close to "A San", they have the title of "A San".
Third, in the past, Indians arrogantly claimed that the United States was a pole and the former Soviet Union was a pole, because they were leaders of the Non-Aligned Movement (a loose alliance composed of dozens of countries in Asia, Africa and Latin America), and as leaders of the Non-Aligned Movement, they were well-deserved roofs of the world. Therefore, China people nicknamed them "Ah San".
Fourthly, civil servants (especially police officers) in the British system have long been used to being called Mr, and Shanghainese have always been used to adding an "A" before monosyllabic words. So after the Shanghainese shouted, they called Ah Sir Ah San.
Fifth, what netizens said today. India has always wanted to be the boss, but aren't there still the United States and Russia ahead? So no matter how many rows, it's three. Therefore, it is called "A San".