Business organisations all over the world are striving hard to evolve strategies to survive in the new era of competition ushered in by globalisation. Global Supply Chain Management (GSCM) is one such strategy. In this paper, various countries across the world have been separated on the basis of various regions and development in their respective economies. To compare the degree of implementation of an ideal supply chain in these countries, a Supply Chain Management Index (SCMI) has been formulated with the help of questionnaire survey and analysis. The difference between the SCMI of underdeveloped, developing and developed nations with respect to the ideal SCMI has been evaluated by using the method of gap analysis. Various strategies have been suggested for different economies in the world for optimising their supply chain network and improving its respective SCMI. Opportunities and challenges offered by the global supply chain, as suggested by various experts, have been pointed out and discussed thoroughly. The effect of bullwhip on global supply chain has also been analysed. Further, the factors affecting the GSCM have been identified and discussed.