How come Han population in Xinjiang has risen from %6 in 1949 to %41 today?

Because China wants Uyghurs to be in minority to deny the claim that Xinjiang has been historically and culturally Uyghur's land.

Typical of communist tradition of falsification of history!

I once read a history book that described the difference between the americans and the chinese when dealing with conquered territories.

He said that the americans, specifically when they conquered the wild wild west, went there and tried to remove all the original inhabitants by pillaging and killing. There was no desire to mix white americans with native peoples.

The Chinese during its long history, always moved their populations into conquered lands and encouraged intermarriages. In time, the people of the conquered regions will become "chinese". Since the Han population is always more dominant, it is an asset as well. Therefore assimilation is prefered. Now that does not mean there were no killings etc but generally speaking.

Now the minorities has three choices: either assimilate into new "mainstream" society, emigrate elsewhere (like the ancestors of the vietnamese, thais etc) or remains to be "minorities" while still retaining her or his own culture.

Needless to say, the modern chinese government has been merely continueing this practice since ancient times.

Citizens are free to go wherever they want within their country. You asking this question is like asking why is there more African-Americans in northern parts of US today than decades ago.

http://www.youtube.com/watch?v=AASpdBvDV1c&feature=channel_page
Listen what the woman says at 1:35 of the video, maybe it will be clear to you then.

it could be because of air quality, nice weather, or something else that's good about the province