Why do people say Asians and not another word like Fareasterns, etc?

Asian is a broadly general term. Chinese, Japanese, Koreans, and other people who look similar number around 1.7 billion (1.35 billion china, 0.15 billion japan/korea, 0.20 billion those who look similar including emmigrants and their descendants, etc) and are actually a minority compared to the 3.9 billion total in asia which can be many different looks like pakistani, saudi, russian, indonesian, etc. in fact in the UK and much of the commonwealth world the word "Asian" more often refers to Indians, Pakistanis, etc.