This is a critical edition of Ibrāhīm ibn Yaʿqūb's account of his trip to Slavic countries at the end of the 10th century. It presents a translation (from Arabic) and interpretation of Ibrāhīm ibn Yaʿqūb's account with philological commentary, a reconstruction of the biographical identity of Ibrahim Ibn Jacob of Tortosa and an identification of the date of his trip. Pieces of information given by Ibrāhīm ibn Yaʿqūb (or added by Al-Bakri from other sources) contain a number of facts regarding the social, economic, and political development of the entire Slavic world in the early middle ages.