West Punjab
At Independence there was a Muslim majority in West Punjab with significant Hindu and Sikh minority. Nearly all of these minorities left West Punjab for India, to be replaced by large numbers of Muslims fleeing from the opposite direction. The official language of West Punjab was Urdu but most of the population spoke Punjabi using the Shahmukhi script. The linguist George Abraham Grierson in his multi volume Linguistic Survey of India (1904–1928) considered the various dialects up to then called "Western Punjabi", spoken in North, West, and South of Lahore in what is now Pakistani Punjab, as constituting instead a distinct language from Punjabi. (The local dialect of Lahore is the Majhi dialect of Punjabi, which has long been the basis of standard literary Punjabi.) Grierson proposed to name this putative language "Lahnda", and he dubbed as "Southern Lahnda" the coherent dialect cluster now known as Saraiki spoken in Multan Dera Ghazi Khan and Bahawalpur division and "North Lahnda" now known as Potwari spoken in Rawalpindi division and "Western Lahnda" now known as Hindko spoken in the regions bordering Khyber-Pakhtunkhwa.
History of the Punjabi language
Punjabi is an Indo-Aryan Language developed from Old Indo-Aryan Languages, which were closely related to Vedic Sanskrit and Classical Sanskrit. By 300 BC Old Aryan Languages developed into many local dialects known as Middle Indo-Aryan dialects. Literary from these dialects was known as Prakrit. Shauraseni used in Eastern Punjab and Kaikeyi used in Western Punjab were among the famous Prakrits of ancient Indian Subcontinent. By 500 AD these Middle Indo-Aryan dialects had been developed many local features and lost many inflectional morphemes. Literary form of these dialects is known as Apabhramsha (ਅਪਭ੍ਰੰਸ਼,اپبھرنش). Principle Apabhramshas are Takka Apabhramsha in Central Punjab and Vrachada Apabhramsha in Southern Punjab. By 1200 AD these Apabhramshas or 'corrupt dialects' had few inflectional morphemes left. During Middle Ages Takka Apabhramsha developed into Lahori dialect and Vrachada Apabhramsha developed into Multani dialect.