▁The ▁S lav ic ▁territ ories ▁were ▁mostly ▁abandoned , ▁because ▁the ▁C elt ic ▁and ▁German ic ▁tribes ▁that ▁lived ▁there ▁before ▁had ▁moved ▁west . ▁Chron olog ically , ▁the ▁first ▁group ▁of ▁S lav s ▁were ▁those ▁that ▁dw elt ▁by ▁the ▁D nie per ▁River , ▁the ▁second ▁was ▁the ▁Su kov - D z id z ice ▁type ▁S lav s , ▁and ▁the ▁last ▁were ▁groups ▁of ▁A var o - S lav ic ▁pe op les ▁from ▁the ▁Dan ube ▁river ▁areas . ▁In ▁the ▁early ▁ 9 th ▁century , ▁the ▁settlement ▁stabil ized . ▁Local ▁S lav s ▁started ▁to ▁ere ct ▁defence ▁systems , ▁such ▁as ▁S iles ian ▁Pr zes ie ka ▁and ▁the ▁S iles ia ▁W alls ▁to ▁guard ▁them ▁from ▁the ▁pe op les ▁of ▁the ▁West . ▁The ▁north - e astern ▁border ▁with ▁S lav ic ▁Pol ans ▁was ▁not ▁rein for ced , ▁due ▁to ▁their ▁common ▁culture ▁and ▁language . ▁ ▁The ▁ 9 th - century ▁Bav arian ▁Ge ograph er ▁records ▁the ▁trib al ▁names ▁of ▁the ▁O pol anie , ▁D ados es ani , ▁Gol enz izi , ▁L up ig la a ▁and ▁the ▁Ś l ęż anie . ▁The ▁ 1 0 8 6 ▁Prag ue ▁Document , ▁which ▁is ▁believed ▁to ▁document ▁the ▁ 1 0 th - century ▁settlement s , ▁also ▁mentions ▁the ▁Bob rz anie ▁and ▁Tr z eb ow ian ie ▁tribes . ▁Later