Complex sentence: This Maratha plunder of Delhi weakened the Mughal Empire, which got further weakened after successive invasions of Nadir Shah (1739) and Ahmad Shah Abdali (1750s) leading to end of Mughal Empire by year 1757 in which Marathas became the de facto rulers of Delhi.
Split into simpler sentences: This Maratha plunder of Delhi weakened the Mughal Empire, which got further weakened after successive invasions of Nadir Shah (1739) and Ahmad Shah Abdali (1750s). The continuous attacks led to an end of Mughal Empire by year 1757 in which Marathas became the rulers of Delhi.