Abstract. – The colonial history of the present-day Guarayos is relatively little known. The article proposes a possible way of reconstructing it by linking it with the history of the Itatin Indians of the eastern bank of the Paraguay River, while insisting on the diverse Guarani legacies that formed modern Guarayo society. During the 18th century, the last migrations of the Itatin to the Chiriguania region are as well the last episode in a shared history of the ethnic groups of both banks of Paraguay River. [Paraguay, Guarayos, Itatines, Kaiowá, Jesuits, bandeirantes]