In America, there are numerous orthodox religious groups which adhere to a lot of customs from hundreds of years ago, for example dressing in a 19th century style. The classic example being the Amish. Other examples are the FLDS and Chassidic Jews.
My question is – are there similar groups outside of Judaism and Christianity?
Some Mennonite sects adhere to the same dress standards as the Amish do, but they live a more modern lifestyle, at least as regards machines, cars, etc.
Crunchy -granola hippies?
I have no idea about the details, but in Uttar Pradesh state in India I stayed with some friends of one of my friends in the countryside. They explanation I got was that the village was fairly rich, but they chose to live “like poor people”. They stuck with dung-burning stoves, communal pit latrines, etc. even though they could well afford these luxuries. No idea if there was a religious element to it or not.