Complex sentence: Subsequently, after arriving in Afghanistan, Islam closed the era of peaceful policies and began a struggle against Pakhtoonwali, Pakhtoon nationalism and Afghan nationalism and abolished all the Pakhtoon kingdoms as they crushed others on its route of expansion.
Split into simpler sentences: Subsequently, after arriving in Afghanistan, Islam closed the era of peaceful policies. Islam began a struggle against Pakhtoonwali, Pakhtoon nationalism and Afghan nationalism and abolished all the Pakhtoon kingdoms as they crushed others on its route of expansion.