The purpose of the article is to present the linguistic and cultural borderland in unofficial anthroponyms and microtoponyms from the district of Jarosław, whose eastern border largely coincides with the border of Poland and Ukraine. Borderland means the sphere of contact and coexistence of various phenomena on the border of geographical neighborhood, but also on the level of language and cultural properties as well as the linguistic and civilizational awareness of the inhabitants of a given area. The analyzed names are characterized by East Slavic and South-East borderlands’ influences, visible mainly in the field of phonetics and word formation, making these names broadly understood linguistic hybrids, i.e. linguistic forms combining phonetic and morphological elements of different languages. The best persistent East Slavic linguistic features in both unofficial anthroponyms and microtoponyms are phonetic properties in the form of g and h pleophony and substitutions, and hybrid derivatives. The constant presence of Ukrainian and South-East borderlands’ lexis and words semantically related to East Slavic cultural and religious realities also deserves attention. All this testifies to the ethnic, social and cultural roots of people living in this borderland.