[thalassophobia]

>they'd be extinct a long time ago if they arrived in China/Middle East/Russia etc.

There is actually a group similar to the Amish in Russia, it's called the Old Believers. They formed after a schism within the Orthodox church and fled persecution to Siberia. Unlike the Amish, many of the Old Believers aren't really integrated with the modern world as they still live where their ancestors settled in. So groups that refuse to technologically progress do exist, and can do so even under persecution and changing economic regimes.