There were two muslim forces and not one working at that time. Moghuls and Afghans. During the time of early moghuls, when this supposedly Sikh protection was happening, ie when the Sikh as martial concept was not there. The Sikhs survived and grew strong because of Moghul's pre-occupation with Marathas. But the sikhs mostly fought with Afghan Invaders cause by that time the Moghuls were very weak. The Punjab was only a gateway during those times and there was nothing in Punjab to loot. The punjab as properous as we see today is after, and due to British. Also keep in mind the Rajput and Jat factor in Khalsa Panth. During Initial days of Khalsa it was Rajputs whoe were mostly fighter Sikhs like Bandha Bahadur, who was a rajput, but then the Jats started to dominate the Sikhs who were extremly anti-brahmins. That took Sikhism away from Hinduism creating its own independent identity. So as they say "Sar Katta ke leiya sardaria ney" lets us see if these Saccha Sodaa's have it in them.
