The history of the foundation of the Brigid nunnery in Brest is complicated, but it can be started by examining the genealogical connections of the people involved in this matter. There are various dates for the founding of the monastery, the most frequently given being 1621 by Kurczewski and 1614 by Swastek. According to them, the foundation is attributed to Jan Pociej and his wife Katarzyna. Several generations of the founding family joined the Brest monastery. The lack of complete sources from the period from the foundation to the partitions makes it difficult to understand the history of the monastery, but fragmentary information is obtained from state records and other institutions or monasteries. Nevertheless, this partial information shows an enduring bond between the founding family and the monastery, suggesting that the foundation was important to many families, both on the paternal and maternal sides.