The introduction of iron into industry really did release new productive forces since for the first time it made efficient metal tools really cheap. All the bloomeries were no doubt exceedingly small so that each firing would yield only a tiny lump of iron. In any case, stone spindle-whorls are among the commonest relics from all Iron Age sites; they indicate a flourishing textile industry. The domestic record of the Iron Age, fragmentary though it be, evidently denotes a much larger population than can be deduced from the funerary record of the Bronze Age. It is true that weapons figure less prominently among the relics of the Iron Age than in earlier stages; only a few spear-heads and sword blades have survived corrosion. The Gallic forts are defended by walls of a pattern and constructed by techniques developed and perfected earlier, during the First Iron Age, in Gaul.