Right, we have an Uighur counter-narrative for the Kunming atrocity provided by anonymous sources to RFA.
“They cannot go back to Hotan, but they cannot do any business in Kunming either because they don’t have any ID cards with them and have arrest warrants issued against them by the regional police department,” the source said.
With no immediate hope in sight, they may have decided to go on a killing spree to avenge the death of their compatriots back home in Xinjiang, according to the source.
“They were likely reacting to the extrajudicial killings that have occurred about a dozen times last year in Xinjiang," the Uyghur said. "Their message to the government was, ‘We can do something also.' "
The initial flashpoint was by this account clashes between Chinese security forces and Uighur protestors in Hanerik, a town in Hotan/Heitian prefecture in Xinjiang last year. That's confirmed by this much more strongly sourced RFA feature from last year, which states that the clashes started after the authorities shut down a local mosque (an informal one?) and took the imam into custody for unexplained reasons. This piece also has allegations of knife attacks against Han civilians.
The overall timeline and wider story here is plausible. What strikes me as improbable is the idea that an inability to get hold of ID cards would cause you to dress in black, arm yourselves with knives and stab more than 160 people.