"European Jewish culture" is not a technology. It doesn't take a huge population base for a group of people to remember their roots and culture and save a lot

"European Jewish culture" is not a technology. It doesn't take a huge population base for a group of people to remember their roots and culture and save a lot of it. But most people are not technologists. Sure, there's a few smart people in a million, but that's not enough to maintain things: medical technology, transportation technology, computer technology, etc. Want a historical example? Look at the fall of the Roman Empire (and also older empires before them). They knew how to make concrete, huge buildings, aquaducts, plumbing, etc. It was all lost when the society collapsed, and that didn't involve killing off most of them, only having them give up on it and move away, and give up on the idea of specialization of labor. It took 1000 years or more to regain the level of technology they had, and really they never did figure out how to make concrete that good until modern times.