The aim of this work is to study the conditions for developing the entrepreneurial ecosystem of regional tourism at the external border of the European Union, in Poland, and its contact points with two non-Union countries (Belarus, Ukraine). The research used a literature review, qualitative and quantitative analyses of the conditions for the development of entrepreneurial ecosystems, interviews with local ecosystem actors and the author’s own observations. The eastern border of Poland (formerly with the USSR) created a barrier to the socio-economic development of adjacent regions. Their peripheral nature has allowed preserving their precious nature value and multicultural heritage. Currently, this preservation constitutes grounds for sustainably developing the region’s tourism. The primary actors of the tourism-based entrepreneurial ecosystem are local governments, public institutions, non-governmental organisations and entrepreneurs. An impetus for activities thereof was granted by Poland’s accession to the EU and its access to Union funds, which has reinforced tourism infrastructure by contributing to the establishment of new tourism enterprises. Furthermore, the development of tourism in the region could also be favoured by the close neighbourhood of as many as two other countries; however, and unfortunately, the border is still a barrier. Apart from the lack of infrastructure allowing borders crossings, political instability in neighbouring countries—made explicitly visible at the border with Belarus in 2021—threatens border-driven tourism by restricting tourism entrepreneurship, especially in those activities based on the access to the border.