The land border areas are key regions for the country to maintain territorial sovereignty, integrity, and security. Since the new century, China has made great achievements in its modernization drive, greatly improving its national strength, and fundamentally altering its border security situation. At the same time, the trend of regional population increase and decrease in China has been directly reflected in these border areas. The seventh national census data show that the total population in border areas across the country has begun to decrease, which has attracted widespread attention from Chinese society. Based on census data, the population change trends in border areas are presented, and the current security situation faced by China's border areas is analyzed. The research results indicate that the current population changes in China's border areas are an inevitable result of China's modernization process and will not adversely impact national defense and security in these areas. In the new era, we need to accelerate urbanization in border areas, reduce the populations engaged in agriculture and animal husbandry, improve the level of economic and social development in border areas, leverage China's modernization to drive the common development of neighboring countries, jointly build a community of shared future for mankind on both sides of the border, and create a higher level of security and stability in border areas.

This paper studies the influencing factors of intermarriage rate in China from 2000 to 2010. The results show that the intermarriage rate of ethnic minorities in China has increased on the whole. There are great differences in the increase of intermarriage rate among different ethnic groups, which can be classified into three types according to the change value of interracial marriage rates and influencing factors. The results of classified regression analysis show that for the first group of the 17 ethnic groups, the change of urbanization rate and the basic value of intermarriage rate in 2000 have a significant impact on the increase of the intermarriage rate; for the second group of the 23 ethnic groups, the change in the proportion of the population with higher education and the change of urbanization rate have a significant impact on the increase of intermarriage rate; While the third group of the 15 ethnic groups has a small or negative increase in intermarriage rate.

Based on data of population censuses in China, this paper briefly describes the development process of the ethnic minority population, discusses the trends and differences in the populations of the ethnic groups in China, and analyzes the characteristics and changes of regional distribution, age structure, mobility, intermarriage and education of the ethnic minorities in China. Combined with the 7th population census bulletin, the paper provides a preliminary judgment on the population situation of China's ethnic minorities in 2020.

Drawing upon data from 2015 China Migrants Dynamic Survey, this article examines trends and patterns of migrant exogamy of China's ethnic minorities. We present estimates of exogamy rates of migrant ethnic minorities by education level, occupation and ethnic group. Compared with the exogamy rates derived from the Sixth Population Census, our results show that the exogamy rates of migrant ethnic minorities are higher than those of the overall ethnic minorities, while the exogamy rates vary across ethnic groups. Compared with the traditional exogamy circle of ethnic minorities, the exogamy circle of the migrant ethnic minorities has undergone great changes. The exogamy rates of migrant women are higher than those of migrant men. Improving educational level of ethnic minority population will play a positive role in promoting migration and exogamy of the ethnic minorities.