The paper presents morphemic-derivational structure of toponymic derivatives (toponymy-derived formations) of proper name “Cибирь”. In revealed derived words authors identify morphemes, specify the methods of their production, provide statistics on word-formation activity of morphemes in the process of secondary nomination of toponymy-derived appellatives. Based on regional material of dialectal dictionaries they define the peculiarities of toponym’s word-formation family of words, as well as its paradigmatic relations with derived categories. Horonym “Cибирь” is considered in the context of perception by regional linguistic persona in the national toponymic space. Examples of semantic toponymy-derived word-formation are given. Thereby, in Russian language world picture it is possible to identify a set of regionally marked background knowledge, perceptions of values as well as historical and cultural characteristics of the analyzed toponym.