ia ▁who ▁declared ▁" Upper ▁S iles ian ▁national ity " ▁( O bers ch les ier ) ▁were ▁assigned ▁to ▁the ▁German ▁national ity ▁category . ▁After ▁World ▁War ▁II ▁in ▁Poland , ▁the ▁ 1 9 4 5 ▁census ▁showed ▁a ▁s izable ▁group ▁of ▁people ▁in ▁Upper ▁S iles ia ▁who ▁declared ▁S iles ian ▁national ity . ▁According ▁to ▁police ▁reports , ▁ 2 2 % ▁of ▁people ▁in ▁Z ab rze ▁considered ▁themselves ▁to ▁be ▁S iles ians , ▁and ▁that ▁number ▁was ▁around ▁ 5 0 % ▁in ▁Str zel ce ▁County . ▁ ▁History ▁Arch ae ological ▁find ings ▁of ▁the ▁ 2 0 th ▁century ▁in ▁S iles ia ▁confirm ▁the ▁existence ▁of ▁an ▁early ▁settlement ▁inhab ited ▁by ▁C elt ic ▁tribes . ▁ ▁Until ▁the ▁ 2 nd ▁century ▁some ▁parts ▁of ▁S iles ia ▁were ▁populated ▁by ▁C elt ic ▁Bo ii , ▁prede cess ors ▁of ▁the ▁states ▁of ▁Boh emia ▁and ▁Bav aria ▁and ▁subsequently ▁until ▁the ▁ 5 th ▁century , ▁by ▁the ▁German ic ▁Sil ing i , ▁a ▁tribe ▁of ▁the ▁V and als , ▁which ▁moved ▁south ▁and ▁west ▁to ▁in va de ▁And alus ia . ▁S iles ia ▁remained ▁dep op ulated ▁until ▁the ▁second ▁phase ▁of ▁the ▁migration ▁period . ▁ ▁The ▁S lav s , ▁pre domin antly ▁White ▁Cro ats ▁entered ▁the ▁dep op ulated ▁territory ▁of ▁S iles ia ▁in ▁the ▁first ▁half ▁of ▁the ▁ 6 th ▁century .