Ibrahim ibn Yaqub was a Jewish traveller and merchant from Ṭurṭūšah (Tortosa), a city in North-Eastern Spain, which, at that time, was a part of the Caliphate of Córdoba. He was supposed to have been involved in a slave trade. He visited many European countries, where he would write down, apart from the information that were useful in the discharge of a merchant’s duties (like trade routes, prices and quality of goods), also the information about religious relations, population, family customs, diseases and their treatment, and many other peculiarities he observed, by which he showed his broad perspective.
In 965 or 966 he stayed in Magdeburg at the court of the newly crowned Roman Emperor, Otto I of Germany, with whom he talked, which may prove his visit had a parliamentary character. It is also probable that he learned in those court circles of the existence of an authority not known to him before, the “land of Mesko”. The content of the note does not indicate that he was to visit them personally. He wrote down the acquired information in his account, which has not been preserved in whole to this day, and which is known to us due to its use by Arab compilers: chronicler Al-Bakri in the 11th century (in his work entitled Book of Highways and of Kingdoms) and cosmographer Qazwini of Damascus in the 13th century (Book of Monuments of the Countries).
Since the 1878 edition prepared by W. Rosen and A. Kunik, the text of the Ibrahim ibn Yaqub account has been eagerly used as a source describing the functioning and organisation of the state of Mieszko I, including valuable information about the military in the early-Piast monarchy. According to Ibrahim, the strength of this largest of the Slavic countries state relied on effective and well-managed military units, which comprised, as estimated, 3000 men.
