Across Tibetan villages in south-west China, Communist Party officials have been spreading top leader Xi Jinping's gospel of national unity: that every ethnic group must fuse into one indivisible China with a shared heritage dating back more than 5,000 years.

Thousands of officials in Ganzi, a Tibetan region of Sichuan province, have been paired with families to collect information and give out gifts of rice, cooking oil and beatific portraits of Mr Xi - all to hammer home his message of an encompassing Chinese identity - from Xinjiang in the west to the contested island of Taiwan in the east.