How they managed to construct Pyramids, and if I recall, how Mediaeval Blacksmiths cast chain mail etc etc are mysteries, but do not speak of greater intelligence than is evident today, just some knowledge they acquired, and then was lost.
Phizzy,
Mediaeval construction techniques for chain mail are extremely well known. A piece of metal would be drawn into wire, this would then be heated and wound around a former to create a tight spiral. Individual rings would be cut off the spiral with a chisel giving you open individual loops with a twist. Once you have a large quantity of these rings they would be 'knitted' together to form the chainmail and then the loops would be closed with pliers. The more interlinking of the individual rings you had the better (and more expensive) the mail. Some were riveted as well to provide additional protection.
Making chainmail is exactly the same today, the skill is in the assembly of the mail, there is no easy way to do it and it is very labour intensive. It is very difficult to get it to fit properly without sagging or reducing your movement.
The other main drawback to mail is the weight which is why eventually it was just used to cover the gaps in full harness (plate armour)
Chain mail is never cast.
Sorry for the off topic post, but mediaeval armour and history is very interesting to me.