There are sounds the Uighur residents of Urumqi will not easily forget. The streets around their homes were silent in the midday heat on Tuesday as the city remained in lockdown following the Uighur-led riot on Sunday. But suddenly, the scrape of metal or bump of wood on the pavement would pierce the eerie silence, sending anyone outside scurrying for refuge.

Two days after the worst ethnic unrest in China since the Cultural Revolution their Han Chinese neighbours got angry.