Aurangzeb’s death had created a void in the Mughal empire which none of his successors were able to fill. Nadir Shah, who from being a chief of dacoits had become the king of Persia, saw the weak empire as an opportunity. In 1738, Nadir Shah proceeded to invade India. He overran the western frontiers of Mughal empire capturing Ghazni, Kabul and Lahore in 1739. Soon Nadir Shah stormed Punjab. Muhammad Shah lead the forces himself against Nadir shah. On 13 February, the battle of Karnal was fought. Emperor Muhammad Shah had a force of over a hundred thousand against Nadir Shah’s 55,000 men but was still decisively defeated. the Emperor himself met Nadir Shah in his camp and abdicated, thirteen days after the battle of Karnal. He handed over the keys of the Delhi gate and entered Delhi with him.
At first everything was cordial between the two emperors. However rumours spread throughout Delhi that Nadir Shah had been assassinated. The masses attacked the Persian force and slaughtered 900 Persian soldiers. As Nadir Shah heard of this he straightaway rode into the city, in the city he saw the corpses of Persian soldiers lying on the streets. He was enraged, he ordered a general massacre at all those localities where the bodies of Persian soldiers were found. Consequently on 11th of march 1739 citizens of Delhi were plundered and slaughtered. The massacre continued and at least 30,000 people died on 22nd March 1739. The Emperor went to Nadir Shah to plead for mercy and thus he stopped the massacre and turned to looting the Mughal treasury. The famous Peacock throne, the Darya-e-Noor diamond and unimaginable wealth was looted.
Muhammad Shah was crowned as emperor by Nadir Shah himself on 12 May, and Muhammad Shah ceded the area west of the Indus to Nadir Shah. They both switched crowns according to the Persian tradition of friendship and the Koh-i-Noor diamond was also lost. Nadir Shah’s invasion did a irreparable damage to the Mughal empire. Mughal provinces across the Indus were seceded to the Persians. Later on inspired by the antics of Nadir Shah his successor Ahmad Shah Abdali too invaded India several times between 1748 and 1767 and plundered Delhi.