In Xinjiang province, China, more than 1 million Uighurs and other Muslim minorities are being held in 're-education' camps that the government claims are benign vocational centres teaching useful career skills. But former camp detainees have described them as de facto prisons implementing mass brainwashing and obedience to the Communist party. As more evidence emerges of torture, forced sterilisation of women and other methods of population reduction, should the situation in Xinjiang be termed a genocide? The Guardian's Lily Kuo explains.