From 1395 the city was the centre of an appanage principality belonging to Uladzimir Al'herdavic and his successors, the Alel'kavic family. The last heiress of the Alel'kavic family married Janus Radzivil and when she died in 1612 the city was given to the Radzivil family . In the 17th century Slucak was one of the most significant cities in the country. Despite several crises, such as the threat posed by the Crimean Tartars, wars with Russia and internal conflicts, Slucak was a famous trade and manufacturing centre. The city was under the patronage of the Radzivil family, who were protectors of the reformist and orthodox faith.
Several examples illustrate the development of the city.
In 1581 a print workshop was opened and in 1617 the Slucak Calvinist grammar school was founded. Later, in the 18th century, the theatre and ballet school were founded. In fact, the Protestants were so well protected that many other Calvinists came to Slucak, even from abroad, fleeing persecution at home and seeking the protection of the Radzivil family. In the 17th century, for example, a great number of Scottish colonists settled in and around Slucak. With their knowledge and experience they made an important contribution towards the development of trade and manufacturing processes.