Detentions come amid heightened security and sureveillance during ruling Communist Party congress in Beijing.
Chinese authorities have destroyed more than 4,700 homes and forced about 4,800 residents to leave the complex.
Local residents are also warned not to discuss politics or share news or photos with outside contacts.
Chinese officials force the move, citing concerns for the environment, a local source says.
But Chinese travelers and trade goods cross without delays, a local source says.
In a practice previously ignored by police, they had brought small quantities back to sell to friends in need.
They had been moved before from traditional grazing areas, and now must move again to make way for tourist development.
Chat group organizers must guard against discussions that threaten China's 'interests,' authorities say.