> Areas that used to be mostly white or mixed were now entirely indian.

I've worked in a company where this shift happened in front of my eyes.

Basically I concluded that they have very clear people/employee hierarchy therefore Indian who is in top-position will rather deal with another Indian as a lower worker because he will be able to order him around like a puppet. Therefore he will vouch to hire more Indians.

This may sound like a generalisation and it probably is, but I've seen this exact shift of company having less than 10% Indian to 80%+. And i've seen how they treat each other.