The entrepreneurial ecosystem (EE) framework examines the elements and dynamics within a regional setting to promote productive entrepreneurship. However, from research about foreign entrepreneurs, we know that not all entrepreneurs within a regional context have equal access to resources and networks, giving rise to several forms of sub-structures within a regional setting. We thus raise the concern that EE elements and structures do not equally account for the accessibility and availability of entrepreneurial sub-populations and that such constraints likely promote sub-ecosystem emergence. Our empirical study of the EE of Shanghai from a foreign entrepreneurial perspective covers the period from 2019 to 2023 by drawing on interview data, on-site observations, and archival data, thus addressing how foreign entrepreneurs embed themselves within the EE. Our findings reveal a foreign entrepreneurial sub-ecosystem emerging from the intertwined impact of ecosystem constraints and assets of foreignness. Yet, ecosystem dynamics enhancing ecosystem constraints have a self-reinforcing effect on the decline of the foreign entrepreneurial sub-ecosystem, subsequently diminishing foreign entrepreneurial activities.