On a quiet street in the ancient Silk Road city of Kashgar, a house lies empty, padlocked from the outside, the family who lived there gone. The father was detained in February; three months later the mother was also taken away by authorities. They had allegedly shared extremist Islamist content on their mobile phones, family friends said. Despite protests from relatives, two of their children, aged 18 and 15, were then detained and their younger two, aged seven and nine, were sent to a state welfare centre.