Slawno and Slupsk have the oldest metrics among all castle-towns of Middle Pomerania. Their rising can be dated (basing on the archaeological material) on 9th and 10th century. At first, the prior town centre was Slawno – the later tribal residence of dukes called Ratiborides. Only in the half of 13th century Slupsk shot ahead becoming the main centre of local statehood. For the first duke of Slawno Ratibor I was acknowledged. He was the founder of Joannites cloister building, mentioned in the papal bull from 1238. Swietokrzyskie Annales give information that in 1119 the Polish king Boleslaw Krzywousty defeated two Pomeranian dukes in the battle in Naklo (near Kolobrzeg) - Wartislaw I, the duke of West Pomerania (House of Griffins); and Ratibor of Slawno (father of Ratibor's I, the founder of the Joannites). Because both dukes had close family ties, they collaboratively proceed against Boleslaw Krzywousty. In consequence of this campaign and conquest, the dukes of West Pomerania and Slawno acknowledged supremacy of the Polish king, admitting the obligation of tribute and military assistance on anabasis.

One of the main conditions of dependence was acceptance of Christianity by Pomeranian society. Christianization of Pomerania, Boleslaw Krzywousty entrusted to German bishop Otto of Bamberg. The lands of Slawno and Slupsk were included into the Pomeranian bishopric, with the capital in Wolin. This fact is certified with the protective bulla of Innocent II in 1140, and later bullae; Clement III on 1188 and Honorius III in 1217. The dukes of Slawno were subjected to direct suzerainty of seniors of district Poland; Wladyslaw II the Exile, Boleslaw IV the Curly and Mieszko III the Old. The son of Mieszko the Old, Boleslaw of Kuyavian got married with Dobroslawa - the Pomeranian duchess, the daughter of Ratibor I (Duke of Lands of Slawno and Slupsk). The marriage was solemnized presumably about 1179. The intimitate Polish-Pomeranian relations were weakened after the Lubeck homage in 1181 especially after approval by Bogislaw I supremacies of Denmark in 1185. This dominance made the completely new legal position on Middle and Western Pomerania.

The Slawno lands became for a longer time a fief of Denmark, and the Slupsk land was under Danish occupation and direct rule. It is confirmed by so called Gniezno falsification, which declares that the king of Denmark occupied Slupsk for a couple of years. The Slupsk castellany was a marriage property of Slawno duchess Dobroslawa and probably got on under the Danish rule in consequence of renouncement of that land by Duke of the province of Greater Poland and High Duke of all Poland Wladyslaw III Spindleshanks to Valdemar II king of Denmark. At that time in Slawno Ratibor II ruled. He titled himself as the prince of Slawno Land (princeps dictus terre Slauensis).

Soon a war broke out which ended with an overthrow of Valdemar II in decisive battle near Bornhoved (on 22 July 1227). The battle had a fundamental meaning for the break-up of the Danish domination over Western and Middle Pomerania. Probably because of the break-up of Danish rule, the Slupsk Land was annexed by duke Swantopolk II the Great to Duchy of Gdansk (Pomerelia) about 1226. The Slawno Land was annexed to Duchy of Szczecin after the death of Ratibor II in 1227.

After the death of duke Swantopolk II, the Slupsk Land stayed at Gdansk Pomerelia. In 1274 Margraviate of Brandenburg made an arrangement with Gdansk duke. They received the Slupsk Land into fief. After the unification of Pomerania with Great Poland the renewal of the Polish Kingdom came. Right after the taking into possession Pomerania, the duke of Great Poland Przemysl II was crowned the king of Poland in 1295 in Gniezno. Just after his death (1296), Pomerania together with Slupsk and Slawno Land, ran into the possession of the successor Przemysl II, the duke of Kuyavian Wladyslaw I the Short or Elbow-high. That duke, after only a few years of reign, was deported by Vaclav II, the Czech king, who was crowned in Gniezno (1300) as the king of Poland.

In 1306 the Czech king Vaclav III was murdered (the successor of Vaclav II). Together with him, the dominant Czech Premyslid dynasty died off. That situation was used by Brandenburg margraves and in the autumn 1306 they attacked the west part of Gdansk Pomerelia planning to occupy it by force. They met however, determined resistance of Swiecowie, the outstanding noble family magnates of the Slupsk Land. Swiecowie prosecuted numerous territorial duties and governorships in the final phase of the Czech rule on Pomerania in that time. In the summer 1307 Swiecowie made an arrangement (peace treaty) with margraves of Brandenburg in Ledowo near Ustka, and the Slupsk Land went over under the brandenburgian rule.