Strabo said that Ierne (written Ἰέρνη, meaning Ireland) is under 5000 stadia (7.1°) north of this line. These figures place Celtica around the mouth of the Loire river, an emporium for the trading of British tin. The part of Ireland referenced is the vicinity of Belfast. Pytheas then would either have crossed the Bay of Biscay from the coast of Spain to the mouth of the Loire, or reached it along the coast, crossed the English channel from the vicinity of Brest, France to Cornwall, and traversed the Irish Sea to reach the Orkney Islands. A statement of Eratosthenes attributed by Strabo to Pytheas, that the north of the Iberian Peninsula was an easier passage to Celtica than across the Ocean, is somewhat ambiguous: apparently he knew or knew of both routes, but he does not say which he took.