Several generations of historians and archaeologists have debated the meaning of the word civitas used in Frankish sources in the 9th and 10th centuries. This argument principally involves a short geographical tract whose anonymous author is known as the so-called ‘Bavarian Geographer’. The 9th-century civitas has been interpreted as designating either a stronghold or, according to the definition in classical Latin, a district. Although the former meaning now seems to have gained popularity in recent scholarship, the latter has still not disappeared and, most importantly, the reasons underlying the adoption of either of these definitions have remained unclear. In this article, the evidence in Frankish written documents is systematically analysed and it is concluded that the so-called ‘Bavarian Geographer’ certainly used the word civitas with the meaning of stronghold, which was common in his time and place, and not with the meaning of district.