Silesia in the Early Middle Ages was inhabited by six Slavic Polish (Lechithic) tribes, their names were recorded in Latin as:
1. Sleenzane - around Wroclaw and at the Sleza river, and Mt. Sleza
2. Dadodesani - in the region around Glogow
3. Opolini - in Upper Silesia, in the region of Opole
4. Golensizi - in the region of Raciborz-Cieszyn-Opawa
5. Poborane - along the lower and middle course of the Bobr river
6. Trebouane - in the region around Legnica
If we believe the so-called Bavarian Geographer, in the 800s the strongest of those tribes were the Opolini (who had 20
civitates according to that report), the Dadodesani (20
civitates) and the Sleenzane (15
civitates). The Golensizi were weaker (5
civitates).
It is not certain what actually were those
civitates. According to some scholars, those were
boroughs. According to others, those were
districts (for example each
district inhabited by certain clans, etc.). But it certainly had something to with population size and / or military power (considering that the Bavarian Geographer was a report made by the Holy Roman Empire's spies / intelligence agencies).
According to
Ludwik Krzywicki, after Poland accepted Christianity in 966, Polish church administration divided the land along old tribal borders - and so the Archdeaconate of Wroclaw encompassed former territory of the Sleenzane; the Deaconate of Glogow - areas of the Dadodesani; the Archdeaconate of Opole - traditional homeland of the Opolini; the Deaconate of Cieszyn - lands of the Golensizi.
The border between Lower Silesia and Upper Silesia - also between the Sleenzane and the Opolini - was the Silesian Cutting:
http://en.wikipedia.org/wiki/Silesian_Przesieka
Silesian Przesieka, literally Silesian Cutting (Polish: Przesieka Śląska or Oseg, German: Schlesischer Grenzwald, Hag or Preseka, Latin: Indago) was a densely forested, uninhabited and unpassable strip of land in the middle of Silesia, spreading from Golden Mountains in the south, along the Nysa Klodzka to the Odra, and then along the Stobrawa, reaching the towns of Namyslow and Byczyna in northern Silesia. Originally, the Silesian Cutting was a boundary, separating territories of two Western Slavic tribes, the Slezanie and the Opolanie. In the 12th century, along the Cutting a border of Lower Silesia and Upper Silesia was established.[1][2][3] (...)
Map showing the Silesian Cutting (
red line):
