Analysis of craftsmen's names in medieval records suggests that the major industries of medieval Birmingham were textiles, leather working and iron working, with archaeological evidence also suggesting the presence of pottery, tile manufacture and probably the working of bone and horn. By the 13th century there were tanning pits in use in Edgbaston Street; and hemp and flax were being used for making rope, canvas and linen. Kilns producing the distinctive local Deritend Ware pottery, examples of which can be seen in The Birmingham History Galleries, existed in the 12th and 13th centuries, and skinners, tanners and saddlers are recorded in the 14th century. The presence of slag and hearth bloom in pits excavated behind Park Street also suggests the early presence of working in iron. The borough rentals of 1296 provide evidence of at least four forges in the town, four smiths are mentioned on a poll tax return of 1379 and seven more are documented in the following century. Although fifteen to twenty weavers, dyers and fullers have been identified in Birmingham up to 1347, this is not a significantly greater number of cloth-workers than that found in surrounding villages and at least some of the cloth sold on the Birmingham market had rural origins. This was the first local industry to benefit from mechanisation, however, and nearly a dozen fulling mills existed in the Birmingham area by the end of the 14th century, many converted from corn mills, but including one at Holford near Perry Barr that was purpose-built in 1358.