Punjabi is a language that does descend from the medieval languages used in India.
Some words may be directly linked to sanskrit, some to persian and some to shauresani etc..etc..
There were adaptations of these medieval languages which resulted in punjabi.
But, just like the Sikhism, that came as a religion that was neither hindu or muslim, in effect it was adapted for those times.
Some still regard sikhism as an offspring religion, which it clearly is not.-as it has it's own unique identity and beliefs. Only by learning about it , does one realize this.
Prakashji, you are correct in the sense of saying that adaptation of language results in adaptation of human behaviour. Yes, this is how offspring sects are formed.
This is also the reason why sikhism is considered by some others as an offspring itself.
But, we can't keep going back to see what came 1st, that was not the idea. The idea was to move forward with sikhism and identify it with all things that stood for truth, without tracing backwards.
Guru Nanak ji said 'na koi hindu na musalman'
He didn't say we are all hindu and musalman and we should get on ahead.
He introduced the truth, that is above man made religions.
Followers of this concept are sikhs. Sikhs are unique in this aspect, we don't simply stand for some truthful concepts of islam and hindus put together or a few things from each faith mixed together. BUT, we are followers of the complete and whole truthful concept of one creator.
So,we should steer clear ahead of trying to retrace steps by going back, as going back brings the same mixed confusions of the people then.
Sikhism, even from it's inception was never meant to be a religion.Guru nanak dev ji never set out to form a new religion. It's what the people have made it.
Sikhi and it's teachings was a 'spiritual way of life- for the true lord, living by the truth'
This spiritual way of life exceeded all the religions of that time, it wasn't started to compete or otherwise with them.
The journey is now and ahead.
Waheguru