
Here is a neat bit of ancient technology: A qanat.
A common problem in arid regions is how to get enough water for your irrigation needs. Digging wells is one possibility, of course, but the water table might be far beneath the surface.
However, the neat thing about the water table is that it runs parallel to the surface - so if the terrain rises up and forms a mountain, the water table will rise up beneath the mountain as well. Thus, you can tap the water within the mountain simply by digging a tunnel into the flank of the mountain.
Which isn't exactly a trivial undertaking, of course. Still, some qanats in the Middle East have been in use for several thousands of years.
And for #TTRPG , such qanats represent a good entrance to the "Underdark", or whatever the local "Realms Below" are called - or vice versa, and monsters might emerge from them. And what happens if a qanat suddenly ceases to bring water? Naturally, some daring adventurers have to go in there and solve the problem, or else an entire community might starve!





