[tbw2]

I’d say the pre-computer era, the 1930s, not the stone age, if the breaches essentially shut down the digital age.
We’d go back to the 1800s after mass EMP attacks.
Stone age only comes up if you have EMP plus nuclear attacks across the world.

[GingisK]

We’d go back to the 1800s after mass EMP attacks.

Nah, that takes us back only to the 1940s. Vacuum tubes do OK, actually.