Latin, wich.
In origin, -wic was a place-name element derived from the Latin vicus, place. Its most common meaning is dairy-farm. However, as the Domesday Book clearly shows, the element by itself had evolved the specialised meaning of salt-working by the eleventh century.
The Domesday Wiches are the salt-working towns of Droitwich in Worcestershire, and Middlewich, Nantwich and Northwich in Cheshire. In Cheshire, the place-names have been left in the Latin form, Wich; but in Worcestershire and elsewhere the modern form of Droitwich is given. The modern place-name forms of the Cheshire Wiches have been incorporated in the text as editorial insertions.
The separate treatment accorded to the salt-works in Cheshire, and the large number of references to Droitwich in Worcestershire and several other counties, may be taken as an indication of the significance of the salt-working towns in the economy of the region, and indeed of the country.
I copied all that lot, but as I was born in Woolwich and there are no salt mines there, I would go for the dairy farm option.