Although more and more people realize the important role of the urbanization process on the economic, political and environmental systems along the Belt and Road, the study on urban expansion and form changes is still limited. Based on the latest 300 m resolution global land cover dataset from 1992 to 2015 released by the ESA Climate Change Initiative project, DMSP/OLS night lighting data from 1992 to 2012, and LandScan population data from 2000 to 2015, in this paper we first analyzed the spatial pattern of urban land growth and dynamics in the ten major sub-regions along the Belt and Road from 1992 to 2015. Then, by analyzing the spatial and temporal changes of urban land density in concentric rings in 1992, 2003 and 2015, the expansion and form changes of 80 cities along the Belt and Road were quantified. Finally, the long-term relationships between urban land area, weighted lighting area and urban population were quantified by using three statistical models, including linear, power-law and exponential function models. The results show that the urban land area along the Belt and Road increased from 0.24% in 1992 to 0.56% in 2015, and developing countries in Africa and Asia are major contributors. The density of urban land in the concentric rings is decreasing from the city center to the urban fringe, and the spatial distribution between cities is completely different. Comparisons among cities in China, Europe, Africa, West Asia, Southeast Asia, and India with populations of more than one million, show that, in addition to the decentralization of China's urban form, the overall urban form of other sub-regions became compact. Further analysis results show that the urban economic vitality and urban population distribution trends will affect the urban spatial expansion and form changes at different levels.

With the advancement of globalization and market economy, geo-economic relation has increasingly attracted scholars' attentions. Trade data, including import and export flows, has dominated the geo-economy research owing to its availability and representativeness. However, this might incline geo-economy research toward trade studies and disregard the importance of other international economic components, such as investment. Combining investment and trade data in doing geo-economic analysis could provide us with a more comprehensive understanding of economic relations between countries. Taking China, the US and Northeast Asian countries as an example, this paper explores the patterns of geo-economic relations between these countries, inspects the driving forces and formation mechanism of the patterns, and also makes comparison between China and the US. As a typical region with unbalanced politics and economy and greatly influenced by both China and the US, Northeast Asia can be a salient sample for geo-economic research. A geo-economic streaming potential model is proposed to evaluate comprehensive geo-economic relations which take into account both trade and investment. The conclusions are as follows. First, from 2000 to 2016, the geo-economic relations between China and Northeast Asian countries were strengthened, during which trade flow constantly occupied the dominating position. However, since 2012, the proportion of investment in geo-economy has increased rapidly. Second, the geo-economic flows between China and the US were the strongest with the fastest growth. The geo-economic flows between China and Japan, South Korea were increasing, while those between China and Russia, Mongolia and North Korea had limited influence. Third, both China and the US had expanding geo-economic flows with Northeast Asian countries and similar distribution pattern. Two major differences are also noted. One is that driving forces are different with China's geo-economic relations driven by trade flows and those of the US driven by investment. The other difference is that China's connections with Russia, Mongolia and North Korea have been strengthened while the US has been trying to maintain strong geo-economic relations with Japan and South Korea.

As an expansion area of international cooperation under the Belt and Road Initiative, South America is of great importance for China to enhance geo-economic status and expand geo-economic space. Based on trade, investment, tourism, transportation and politics, this paper establishes a multi-dimensional index system of geo-economic linkages intensity and analyzes the important characteristics of the geo-economic linkages intensity between China and countries in South America by using the gray correlation TOPSIS method and geographically weighted regression model. The results show that: (1) The geo-economic flows between China and South American countries show an overall increasing trend during 2006-2015. (2) China and South American countries have an unbalanced development in geo-economic linkages elements. The geo-economic linkage of transportation is higher than that of politics, tourism, investment and trade. (3) The geo-economic linkages intensity between China and South American countries are at a low level and varies significantly among countries. (4) The geo-economic linkages intensity between China and South American countries is slowly increasing, and the changes in spatial pattern are small year by year. (5) Gross domestic product, population size and cooperative goldenstein factor are the dominant factors influencing the geo-economic linkages intensity between China and countries in South America. Market is the most important driving force for geo-economic linkages intensity between China and countries in South America. Resource endowment has little effect on the geo-economic linkages intensity, while geopolitics has a significant effect on the geo-economic linkages intensity.

Although many theoretical schools have been developed and thrived in the field of "geopolitics" in Western academia over the past 120 years, the influence of geopolitical research has been declining partly due to the lack of concern for realistic issues, which is embedded in its traditional research agenda. In China, geopolitical studies have mostly followed the Western approach until 2010 when a new "geo-setting" research agenda was launched. This geo-setting research agenda incorporates geographic knowledge and politics into the process of geopolitical analysis, which has demonstrated both theoretical and practical significance because it not only brings reform and innovation to geopolitical studies but also contributes to the promotion of the Belt and Road Initiative and the construction of a community with a shared future for mankind. This paper proposes a research approach and an analytical framework for nationa-state based and integrated interdisciplinary geo-setting studies, according to previous academic findings on geo-setting, including conceptualization, leading elements, structure, and simulation. This framework is illustrated by a case study of Japanese geo-setting during the period of Tokugawa Bakufu. From an integrated interdisciplinary perspective, this paper unveils how the Japanese geo-setting had evolved under the combined effects of both domestic and international factors at multiple scales. It also sheds light on Japan's domestic and external policy formulation and changes during the period of Tokugawa Bakufu. Finally, three suggestions are put forward to strengthen the current nation-state based geo-setting research: (1) to continue to apply the interdisciplinary approach; (2) to highlight an integrated approach featured by multi-factor, multi-scale and long-term analysis; and (3) to pay consistent attention to long-term dynamic simulation.