Complex sentence: However, these groups included Sikhs, who are a religious rather than linguistic group, virtually all of whom are Punjabi, which was also captured as a separate'dialect' category (comprising mainly of Hindu Punjabis).
Split into simpler sentences: However, these groups included Sikhs, who are a religious rather than linguistic group. Virtually all of the Sikhs are Punjabi, which was also captured as a separate'dialect' category (comprising mainly Hindu Punjabis).