The area around Criccieth was settled during the Bronze Age, and a chambered tomb, "Cae Dyni", survives on the coast to the east of the town; it consists of seven upright stones, and there are 13 cup marks, arranged in several groups. Evidence from other sites on the Llŷn Peninsula suggests that the area was colonised by a wave of Celtic settlers, who explored the Irish Sea, probably around the 4th century BC. Ptolemy calls the peninsula "Ganganorum Promontorium (English: Peninsula of the Gangani)"; the Gangani were a tribe of Irish Celts, and it is thought there may have been strong and friendly links with Leinster.