Over 3,000 years ago the Assyrians developed a remarkably advanced underwater technique, as illustrated in this ancient relief. It shows Assyrian soldiers using goatskin bags filled with air to breath
Seems implausible, one breath takes close to 500 mililitres of air when resting, these bags even if they work as intended can prolong underwater stay for a minute or two at most.
And how hard would it be to take it under water?
Looks like a floating device for me, that you can refill and empty to take less space
But if you're trained it's different. I agree there was not enough air to last for long, but supposing they were trained divers it could have made a differwnce that was worth it to them.
But why wold assyrians need trained divers at all? They were landlocked and without access to the biggest rivers in the region.
Maybe for funsies. Maybe Mom said they could have friends over to their pool and they wanted tj have fun.
Why do you think 2 minutes isn't enough?
They were soldiers, not fishers. The point wasn't to catch fish or do anything that required to stay underwater for long.
I think that whole exercise is pointless, why would a polity 3000 years ago need an underwater insertion(?) training? Especially if they are lanlocked without any big bodies of water in vicinity. I don't think that most modern armies have more then a handful of people trained for such things and modern armies are infinitely better equipped, trained, and numerous.
Oh look at that guy coming out of the water, should we stab him now or let him get up and out of the water fully first?
Inhaling from the bag and exhaling to the atmosphere, yeah, just a couple minutes before the bag is empty.
Rebreathing the same air by exhaling back into the bag, you'd probably get 5-10 minutes of usable air.