How did the han chinese attempt to assimilate conquered peoples?

I don't know which specific context you refer to - the Han Chinese have conquered many people. 

So I will provide one example - in Taiwan, the aboriginal people were required to have Chinese names in their passports until recently, which means that every person was forced to adopt a Chinese name, and often their original name was dropped, and (over generation) forgotten. This has changed how people self-identify: weakening their indigenous sense of identity.