## 5 Discussion
The high CCD values were mainly clustered in the central areas of Mongolia (e.g., Ulaanbaatar, Tov, and Govisumber). The main reason for this finding may be that the central regions have more convenient transportation [68], are richer in mineral resources [99; 100], and have higher levels of urbanization and livelihood. However, the CCD values of most of the central areas still existed in low-level coordination, which occurs mainly because most of the urban residents who live in ger areas of central areas remain unable to enjoy basic services [7; 10; 15] and suffer from poverty, environmental pollution, and disease [12; 27; 101]. Moreover, the CCD of some western regions is increasing every year, especially in the border areas, which is mainly attributable to the development of border trade. Since 2004, China and Mongolia have opened 18 trade ports that are mainly distributed in Govic-Altai, Umunugovic, and Sukhbaatar [102]. The trade between China and Mongolia has been increasing substantially. The trade volume in 2004 was $694 million and increased to $4.02 billion in 2010 [103]. In 2016, it continued to climb to $4.93 billion [104]. Additionally, the development of the border trade between Mongolia and Russia has also shown good momentum [72; 73]. Border trade has promoted the urbanization level and residents' livelihood level in several western Aimags, such as Govic-Altai, Umunugovic, and Zavkhan. From 2004 to 2016, their CCD values continued to rise, and they engaged in low-level coordination in 2016. However, volatile Mongolian policies, regime changes, and a lack of infrastructure at border ports have also seriously affected the development of some border regions [72; 103], such as Bayan-Ulgii, Selenge, Bayankhongor, and Dornod, and their CCD values were still in the moderate and mild disorder stages. The argument that the CCD is seriously affected by both the economic development level and the industrial development level was strongly demonstrated in the SDM. As shown in Table 4, the coefficient of the spatial lagged value of the secondary industry share was significantly positive in explaining the CCD. As we predicted, an increase in the secondary industry share in an Aimag will promote an increase in the CCD in this Aimag. The rapid development of industry is the main factor in Mongolia's urban development. Since 2004, the development of the mining industry has led to rapid economic growth in Mongolia [22]. In addition, the real estate industry has expanded, and single-family dwellings are increasingly becoming the domicile of choice, which has promoted the development of satellite communities around the city [105]. Furthermore, the mining boom in 2009, combined with the dzud disaster, forced nomads to migrate to cities, especially Ulaanbaatar [80]. Although both the mining boom and real estate development have benefited urban elites more than urban residents [22; 27], the development of a secondary industry has also provided employment opportunities for most urban residents to maintain their livelihoods. Therefore, industrial development can promote the level of urbanization and livelihood level of urban residents, and thus enhance the CCD. Additionally, the economic level is also the most powerful factor that can promote the improvement of the CCD, which was verified by our results, where the coefficient of the spatial lagged value of the registered enterprises per thousand urban residents on the CCD was significantly positive (see Table 4). As a key microeconomic sector, enterprises are of vital importance to urban development [106]. Moreover, enterprises mainly promote urban economic development by raising wages and stimulating consumption [106]. Accordingly, the development of enterprises promotes not only the level of urbanization but also the livelihood level of urban residents. Thus, the increase in the number of registered enterprises can promote improvement in the CCD.