As described in historical dictionaries

Patronymica Britannica (1860)

TREG IAN. Lands so called in the parish of St. Eue, in Cornwall, are supposed to have given name to this family. C. S, Gilbert's Cornwall.

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.


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