Hundreds of workers at a factory in Shenyang in northeastern China weld automated machines, 95 yards long, that are used to bore subway tunnels. At another factory there, employees assemble robots that China’s solar panel makers will use to streamline their production.

Shenyang is the capital of Liaoning province, one of three large provinces in the northeast that constitute the cradle of China’s heavy industry. Now the central government, confronting a national economy that has slowed because of a real estate crisis that defies easy fixes, is turning to cities like Shenyang. It hopes to squeeze more productivity and efficiency out of the region’s factories.

But those factories tell only part of the story of the economy of northeastern China, underlining the challenges facing Beijing policymakers, who are turning to what many economists believe is a tired playbook.