ons ▁Tow ard ▁the ▁end ▁of ▁the ▁ 4 th ▁century , ▁the ▁Brit ons ▁of ▁what ▁is ▁now ▁Wales ▁and ▁the ▁South - West ern ▁pen ins ula ▁of ▁Great ▁Britain ▁began ▁to ▁em igr ate ▁to ▁Arm or ica . ▁The ▁history ▁behind ▁such ▁an ▁establishment ▁is ▁unclear , ▁but ▁medieval ▁Bre ton , ▁An ge vin ▁and ▁Wel sh ▁sources ▁connect ▁it ▁to ▁a ▁figure ▁known ▁as ▁Con an ▁Mer i ad oc . ▁Wel sh ▁literary ▁sources ▁assert ▁that ▁Con an ▁came ▁to ▁Arm or ica ▁on ▁the ▁orders ▁of ▁the ▁Roman ▁us ur per ▁Magn us ▁Maxim us , ▁who ▁sent ▁some ▁of ▁his ▁British ▁troops ▁to ▁Ga ul ▁to ▁en force ▁his ▁claims ▁and ▁settled ▁them ▁in ▁Arm or ica . ▁This ▁account ▁was ▁supported ▁by ▁the ▁Count s ▁of ▁An jou , ▁who ▁claimed ▁descent ▁from ▁a ▁Roman ▁soldier ▁exp elled ▁from ▁Lower ▁Brit t any ▁by ▁Con an ▁on ▁Magn us ' s ▁orders . ▁Reg ard less ▁of ▁the ▁truth ▁of ▁this ▁story , ▁Bry th onic ▁( B rit ish ▁C elt ic ) ▁settlement ▁probably ▁increased ▁during ▁the ▁Ang lo - S ax on ▁invasion ▁of ▁Britain ▁in ▁the ▁ 5 th ▁and ▁ 6 th ▁centuries . ▁▁ ▁Sch ol ars ▁such ▁as ▁Lé on ▁Fle uri ot ▁have ▁suggested ▁a ▁two - wave ▁model ▁of ▁migration ▁from ▁Britain ▁which ▁saw ▁the ▁emer gence ▁of ▁an ▁independent ▁Bre ton ▁people ▁and ▁established ▁the ▁domin ance ▁of ▁the ▁Bry th onic ▁Bre