Quote: Although Lancaster Amish are Pennsylvania Dutch, all Pennsylvania Dutch are not Amish. The Pennsylvania Dutch are natives of Central Pennsylvania, particularly Lancaster and its surrounding counties. Unlike the Amish, they are not all one religion. Instead, their common bond is a mainly German background (Pennsylvania Dutch is actually Pennsylvania Deutsch, or German). They also have Welsh, English, Scottish, Swiss, and French ancestry. Enquote

I believe that the 'plain people', in addition to the Amish and the Mennonites, also include the Hutterites, the Moravians, the Brethren and the Dunkards. There may be more.