Kammala jumla mai zuwa: Belgae da Celts, waɗanda aka sani da Gauls, sun mamaye Normandy a cikin raƙuman ruwa masu zuwa daga ƙarni na 4 zuwa na 3 BC. Yawancin iliminmu game da wannan rukunin ya fito ne daga Julius Caesar "de Bello Gallico". Kaisar ya gano ƙungiyoyi daban-daban a cikin Belgae waɗanda suka mamaye yankuna daban-daban kuma suna zaune a cikin garuruwan gona. A cikin 57 BC, Gauls sun haɗu a ƙarƙashin Vercingetorix a ƙoƙarin tsayayya da farmakin sojojin Kaisar. Ko da bayan shan kashi a
Alesia, mutanen Normandy sun ci gaba da fada har zuwa 51 BC, shekarar da Kaisar ya kammala cin nasararsa na Gaul.