Let me put some points, hopefully we would understand each other.
1) British annexed Punjab is 1843 and Sindh in 1849 and Western Pakistan, later on. This makes their rule a barely 100 year rule on territories of present day Pakistan. Pakistan is acronym for Punjab, Afghania (KPK old name), Kashmir, Sindh and balochisTAN.
2) Central Asian or Arab invaders no way had the might to do mass conversions. If they had, they ruled India for 1000 years, India should have been entirely muslim, but it wasn't, Hindus were represented in corridors of power at the time. Moreover the Islamic Schools of thought of Punjab and Sindh were entirely different from the schools of thought preached by invaders, the locals converted through endeavors of Sufi saints, which were held in high esteem by Hindus and Sikhs alike. Islam spread to Malaysia, Indonesia, Bangladesh, was it by sword then ?
Religions have changed throughout time. Christianity was a Middle Eastern religion, today most of its followers are in west, who used to follow european pagan religions. Same case was with Judaism, which started in Middle East, today most are Ashkenazis, i.e European Jews. Islam started in Middle East, today 70% of its adherents are non Arab.