Why are there more grain depots in Xinjiang than in Yunnan?

Xinjiang has more grain depots than Yunnan. Xinjiang's policy grain purchase is coming to an end. Three million tons of national policy grain are stored in 23 grain depots directly under the Tianshan Mountains. These grains are mainly wheat, and a few warehouses store corn and cooking oil. In Xinjiang, the largest grain depot is located in Yili, covering an area of 400 mu, with 55 granaries and 270,000 tons of grain. The smallest grain depot is located in Hotan area, storing 50,000 tons of grain. Different from commodity grain, the national policy grain right belongs to the State Council, which is allocated by the central government, and no unit or individual may use it to ensure national food security, adjust the total market supply and adjust the market price.