LTReikšminiai žodžiai: Augimas; Formavimasis; Lietuvos Didžioji Kunigaikštystė (LDK; Grand Duchy of Lithuania; GDL); Pagrindinės sąvokos; Reikšmė; Susiformavimo priežastys; Basic concepts; Formation; Growth; Importance, Belarus; Reasons of formation; The Grand Duchy of Lithuania; Baltarusija (Belarus).
ENThe change of the conceptual approaches of the East Slavic historiography of the ХХ century to the problem of the establishment of the Grand Duchy of Lithuania, the role of this state in the fate of the Belarusian people and the current state of this problem are shown in the article. The prerequisites, internal and external causes of the formation of the Grand Duchy of Lithuania are considered. It is traced the activity of the first great princes Mindaug, Voishelk, Vyten to create and strengthen a new state, its growth in the geographical and political space of Europe under Gedymin and Algierd and the value of the Grand Duchy of Lithuania in the history of Belarus. [From the publication]