China has approved a sweeping new law which claims to help promote "ethnic unity" - but critics say it will further erode the rights of minority groups. On paper, it aims to promote integration among the 56 officially recognised ethnic groups, dominated by the Han Chinese, through education and housing. But critics say it cuts people off from their language and culture. It mandates that all children should be taught Mandarin before kindergarten and up until the end of high school. Previously students could study most of the curriculum in their native language such as Tibetan, Uyghur or Mongolian. The law was approved on Thursday as the annual rubber-stamp parliamentary session drew to an end. "The law is consistent with a dramatic recent policy shift, to suppress the ethnic diversity formally recognised since 1949," Magnus Fiskesjö, an associate professor of anthropology at Cornell University said in a university report.…