This article presents theoretical concepts of borderland that come out in Ukraine and are connected with the research on Euroregions and trans-border cooperation. Some of them refer to Mark Granovetter's concept of the 'Strength of Weak Ties', e.g. Jurij Pielewin's concept of 'bridge connections', and Richard Bach - 'The Bridge Across Forever'. The second direction of the theoretical search are concepts of 'borderland sociology' represented in Ukraine by Katerina Szestakowa, Sergiej Gakman and Ewa Kisz. The research on Euroregions and trans-border cooperation refer to theoretical tools applied to analyze inter-regional competition within 'regions marketing' as well.