In the 17th century the Cossacks took part in the Khmelnytsky uprising. The fertile soil of the Udai basin proved itself attractive not only to marauders, but also to hard-working people fleeing from backbreaking toil. The number of inhabitants of Pryluky and adjacent villages grew considerably in the 17th century. One of the documents kept in the archives of Stockholm, Sweden stated that there were 800 chimneys, i.e. 800 houses, in Pryluky in 1632. Assuming that each house accommodated at least six persons, about 5,000 people lived in the city at that time.