This study introduces a collection of manuscripts of Münşeʾât ve Baʿżî Vaḳâyiʿ-i Sulṭân Süleymân Ḫân that are preserved in the Austrian National Library with the signature of H.O. 50. This research aims to shed light on the history of Ottoman-Safavid relations through their direct correspondence. Furthermore, it checks the accuracy of the printed version of documents Mecmûʿa-i Münşeʾât üs-Selâṭîn (Istanbul, 1858), which are a major source of the two medieval empire of Iran and Turkey, as modifications have already been demonstrated by distinguished scholars such as Kurt Holter. The results of this study show that the aforementioned manuscripts contain 75 documents, including letters and campaign diaries. A total of 32 letters and one campaign diary are related to the relations during Ottoman ruler, Suleiman I and Ismail I and Tahmasp I of the Safavid Empire. In addition, correspondence of these two empires from Münşeʾât ve Baʿżî Vaḳâyiʿ-i Sulṭân Süleymân Ḫân can be found in Mecmûʿa-i Münşeʾât üs-Selâṭîn (Istanbul,1858).
