The first mention of Miercurea-Ciuc as a country-town (lat. oppidum) occurred in a 16th century charter. The privileges offered by Queen Isabelle to Miercurea-Ciuc in 1558 guaranteed tax exemption for its citizens, the only exception being the tax due to the Ottoman Empire. All of these rights contributed to the economic development and demographic increase of the town.
The letter of privilege issued by Queen Isabelle was later confirmed by other princes of Transylvania, such as Sigismund Rákóczi in 1606 and Gabriel Báthori in 1608. After ascending to the throne, Prince Gabriel Bethlen deprived the city of its former rights and gave the town as a gift to his loyal servant, Franciscus Mikó, who meanwhile also become the Supreme Captain of Ciuc Seat. Since Mikó originally came from outside the Ciuc Seat, he needed local fief to occupy the newly appointed position. This might be one of the reasons why the town was given as a gift to him. Another motive could have been the construction of the Mikó Castle, an enterprise requiring both financial and human resources. Despite his efforts to stop the institution of serfdom among the Székelys, Prince Bethlen also disposed the incomes of the town to Mikó, the new feudal lord, and forced the locals to take part in the construction of the castle as serfs. After Mikó’s death in 1635, the town requested Prince Georgius I Rákóczi to restore its old privileges. The plea was heard, and in the same year, the prince returned to the locals their old civic rights. Later, the deed of gift issued by his son, Georgius II Rákóczi, also reinforced these privileges. In 1670, another town charter was given to Miercurea-Ciuc by Prince Michael Apafi I, which is now kept by the Székely Museum of Ciuc. The significance of the latter charter is evident by the fact that it contains the text of the earlier patents mentioned above since their originals did not survive.
