In those days ice was transported from mountain regions to towns and cities, so that, for example, wealthy families could have interesting desserts at their banquets. And I imagine some market-sellers might have used it to keep their produce fresh - displaying sea-food in an ice-tray, for example. Internet sources are a bit vague on the technology, but an obvious problem is how to transport the ice without too much of it melting. All I can do is make reasonable guesses. As a form of heat-insulation, there was probably nothing better than wool. I'm thinking raw wool packed in hemp sacks. But, of course, if that was all you used, it wouldn't last long. As soon as the ice melted at all, it would melt fast, because it would soak the wool, which would cause it to cease being a good insulator. So you'd need an inner layer of water-proofing. In those days it could only be animal hides, though I suppose metal drums is a possibility. I'd incline towards the former, because transport from mountain regions, at least in the initial stages, couldn't involve wheeled vehicles. It would have to be carried by mules or donkeys, and weight would be a big consideration. I don't know how porous leather is in its natural state, but treated with some kind of oil, or coated with tar, it might be quite effective. What I can't even guess at is how long the ice could be expected to last, supposing that the buyers stored it under the same conditions, and preferably in a cool cellar. Is it feasible to expect that, say, half of it would still be frozen after a week? All thoughts on all aspects are welcome.