The original sentence is clear and grammatically correct. However, if you're looking for a variation, the second choice maintains the clarity while slightly changing the structure. Here's how the choices rank in terms of clarity and grammatical correctness:
-
Also known as the “Pennsylvania German,” these emigrants settled in southeastern Pennsylvania between the seventeenth and eighteenth centuries because they wanted to escape religious persecution in their home communities. (Correct as is)
-
Also known as the “Pennsylvania German” because they wanted to escape religious persecution in their home communities, these emigrants settled in southeastern Pennsylvania between the seventeenth and eighteenth centuries. (This is also correct, but the introductory phrase may be slightly misleading in the context.)
-
Because they wanted to escape religious persecution in their home communities, also known as the “Pennsylvania German,” these emigrants settled in southeastern Pennsylvania between the seventeenth and eighteenth centuries. (This option is grammatically correct, but the placement of the appositive may cause confusion about what "they" refers to.)
-
Correct as is. (This is simply reaffirming the original statement without any changes.)
Ultimately, the original sentence is the clearest and most effective option.