The article deals with the problematic issues of tracing and dating the fortifications of the city of Bolgar in pre-Mongol times (from the end of the 9^th to the beginning of the 13^th centuries). On the basis of topographic referencing of the excavations, in which the filled ditches were discovered, all the data available on the placement of the defense lines of the early Bolgar are systematized. There is not enough data to exactly date them, therefore, the sequence of appearance of these lines is not obvious. The ditches indicate that there were ramparts next to them, the earth of which was used for the subsequent filling of ditches. Interesting tracks, on which, immediately after filling the earlier ditch, a new one was pulled out, with an indent to the outside. The task of new studies of the early fortifications of Bolgar will be to clarify the dates of their creation and spatial distribution.