▁the ▁Dé isi ▁M uman , ▁E ó gan acht ▁Ch ais il ▁and ▁É ile ▁of ▁Mun ster ▁to ▁the ▁south ▁and ▁west . ▁ ▁The ▁name ▁Os ra ige ▁is ▁said ▁to ▁be ▁from ▁the ▁Us da ie , ▁a ▁C elt ic ▁tribe ▁that ▁P to le my ' s ▁map ▁of ▁Ireland ▁places ▁in ▁roughly ▁the ▁same ▁area ▁that ▁Os ra ige ▁would ▁later ▁occup y . ▁The ▁territory ▁indicated ▁by ▁P to le my ▁probably ▁included ▁the ▁major ▁late ▁Iron ▁Age ▁hill - fort ▁at ▁Fre estone ▁Hill ▁which ▁produced ▁some ▁Roman ▁finds . ▁Also ▁the ▁interesting ▁bur ial ▁at ▁St oney ford ▁which ▁is ▁of ▁typical ▁Roman ▁type ▁and ▁probably ▁dates ▁to ▁the ▁ 1 st ▁century ▁AD . ▁The ▁Os ra ig he ▁themselves ▁claimed ▁to ▁be ▁desc ended ▁from ▁the ▁É ra inn ▁people . ▁O thers ▁propose ▁that ▁the ▁I vern ic ▁groups ▁included ▁the ▁Os ra ige ▁of ▁the ▁Kingdom ▁of ▁Os ra ige / O ss ory . ▁The ▁Brig antes ▁were ▁the ▁only ▁C elt ic ▁tribe ▁to ▁have ▁a ▁presence ▁in ▁both ▁England ▁and ▁Ireland , ▁in ▁the ▁latter ▁of ▁which ▁they ▁could ▁be ▁found ▁around ▁Kil ken ny , ▁W ex ford ▁and ▁Water ford . ▁ ▁Pope ▁Ad rian ▁IV ▁gave ▁Norman ▁King ▁Henry ▁II ▁of ▁England ▁permission ▁to ▁claim ▁Ireland ▁ 1 1 5 4 . ▁The ▁C is tern ians ▁came ▁to ▁Jer point ▁and ▁Kil ken ny ▁around ▁ 1 1 5 5 / 6