The book presents the nine oldest Ottoman documents from the archives of the Monastery of Great Meteoron, which are among the oldest known so far original Ottoman documents worldwide. These sources are published for the first time. Their palaeographical and diplomatics analysis accompanying the edition of the texts aspires to contribute to the overall picture of early Ottoman paleography and diplomatics in a critical period covering the late 14th and early 15th centuries. In addition, in the historical analysis of the documents, issues related to the early Ottoman prosopography, the problem of the seat of the Ottoman ruler, and topics regarding the local history (i.e. Thessaly, and Meteora monasteries) of the period are addressed.