The food market lanes behind the Dongguan Mosque are Xining's best place to buy Qinghai specialities: Tibetan raisins and dried apricots from the Golmud and Haixi areas; dried chilli pastes and spice mixes in the Hui style; fresh-ground cumin; bags of roasted barley (qingke) for tsampa; and a range of dried medicinal herbs used in both Chinese and Tibetan medicine.
The vendors here are knowledgeable and will generally point you toward their best products if you ask. Prices are fair for locals and reasonable for visitors who are not buying in bulk. The market is busiest in the mornings (8am–11am) and late afternoons (4pm–6pm). Look for the lanes directly north and east of the mosque's main gate.