50% in Strzelce County. History Archaeological findings of the 20th century in Silesia confirm the existence of an early settlement inhabited by Celtic tribes. Until the 2nd century some parts of Silesia were populated by Celtic Boii, predecessors of the states of Bohemia and Bavaria and subsequently until the 5th century, by the Germanic Silingi, a tribe of the Vandals, which moved south and west to invade Andalusia. Silesia remained depopulated until the second phase of the migration period. The Slavs, predominantly White Croats entered the depopulated territory of Silesia in the first half of the 6th century. The Slavic territories were mostly abandoned, because the Celtic and Germanic tribes that lived there before had moved west. Chronologically, the first group of Slavs were those that dwelt by the Dnieper River, the second was the Sukov-Dzidzice type Slavs, and the last were groups of Avaro-Slavic peoples from the Danube river areas. In the early 9th century, the settlement stabilized. Local West Slavs began to erect a series of defensive systems, such as the Silesian Przesieka and the Silesia Walls to guard them from invaders. The north-eastern border with Western Polans was not reinforced, due to their common culture and language. The 9th-century Bavarian Geographer records the tribal names of the Opolanie, Dadosesani, Golenzizi, Lupiglaa, and the Ślężanie. The 1086 Prague Document, which is believed to document the 10th-century settlements, also mentions the Bobrzanie and Trzebowianie tribes. Later sources classified those tribes as Silesian tribes, which were also jointly classified as part of Polish tribes. The reason for this classification was the "fundamentally common culture and language" of Silesian, Polan, Masovian, Vistulan and Pomeranian tribes that "were considerably more closely related to one another than were the Germanic tribes." According to Perspectives on Ethnicity, written by anthropologist V. I. Kozlov and edited by R. Holloman, the Silesian tribes, together with other Polish tribes, formed what is now Polish ethnicity and culture. This process is called ethnic consolidation, in which several ethnic communities of the same origin and cognate languages merge into one. Middle Ages The Silesians lived on the territory that became part of the Great Moravia in 875. Later, in 990, the first Polish state was created by Duke Mieszko I, and then expanded by king Boleslaw I at the beginning of the 11th century. He established the Bishopric of Wrocław in Lower Silesia in the year 1000. In the