The article is devoted to the manuscript of the History of the Tartars written by the Franciscan C. de Bridra, preserved in Zentral- und Hochschulbibliothek in Lucerne. It is still relatively unknown to wider circles of researchers and it existence was first announced by G. Guzman in 2006. After discussing the provenience and manuscript context of the Lucerne manuscript, the textual contents of both now known manuscripts of the work are compared. The nickname of the author of the History of the Tartars and the sources of his knowledge about the Mongols are explained. An attempt was made at assessing the importance of the second manuscript of the History of the Tartars for further research on that work.