The major and native language spoken in the Punjab is Punjabi (which is written in a Shahmukhi script in Pakistan) and Punjabis comprise the largest ethnic group in country. Punjabi is the provincial language of Punjab. There is not a single district in the province where Punjabi language is mother-tongue of less than 89% of population. The language is not given any official recognition in the Constitution of Pakistan at the national level. Punjabis themselves are a heterogeneous group comprising different tribes, clans (Urdu: برادری‎) and communities. In Pakistani Punjab these tribes have more to do with traditional occupations such as blacksmiths or artisans as opposed to rigid social stratifications. Punjabi dialects spoken in the province include Majhi (Standard), Saraiki and Hindko. Saraiki is mostly spoken in south Punjab, and Pashto, spoken in some parts of north west Punjab, especially in Attock District and Mianwali District.
What is primarily divided by social stratifications?