I always wanted to know why 'brown' people didn't feature in the three/four-race theory. Well it turns out it's because the British didn't know how to classify Indians (and I guess the same would go for the browns elsewhere in the world like Central and South America and other parts of Asia. The races of Indians can be any of the following: Caucasoids (mostly North), Australoids (mostly South), Mongoloids (mostly North-East), Negritos (mostly the Andaman Islands).
Either way scientific racism as such was discarded as a valid framework a long long time ago, and now the we humans are classified into 5000 ethnic groups.
To know more on South Asian ethnic groups: https://en.wikipedia.org/wiki/South_Asian_ethnic_groups
To know more on World Demography: https://en.wikipedia.org/wiki/Demographics_of_the_world