The codes of several regions are: North China 0 (Inner Mongolia, Hebei and Shanxi), Northeast China 1 (Liaoning, Jilin and Heilongjiang), East China 2 (Shandong, Jiangsu and Anhui), Southeast China 3 (Zhejiang, Jiangxi and Fujian), Central China 4 (Hunan, Hubei and Henan) and South China 5 (Guangdong and Hainan). When you remember the numbers of these regions, you can know from which region of China it was sent by looking at the first number of the code.