and his free-lances from the Oxus was now subsiding into emasculate debility. During the flourishing period of the Moghul Empire its outposts were at Kabul and Kandahar; but toward the end of Aurangzib's reign his garrisons had been driven out of Afghanistan. As the maintenance of a strong northwest frontier has always been essential to the security of India, the divorce of Afghanistan from the rulership of the Indian plains was in those days sure to be followed by the recurrence of chronic invasions from Central Asia. Thirty years after Aurangzib's decease, Nadir Shah, a Persian soldier of fortune who had overturned the ruling dynasty in Persia, came down through the Afghan passes with a great army. The Moghul emperor made but a show of resistance. Nadir Shah sacked Delhi in March, 1739, added one more massacre to the blood-stained annals of that ill-fated city, wrenched away from the imperial crown all its possessions west of the Indus, and departed home, leaving the Moghul government, which had received its death-blow, in a state of mortal collapse.
The barriers having been thus broken down, Ahmad Shah, of the Abdalli tribe of Afghans, followed two years later. When Nadir Shah had been assassinated by the Persians in his camp in Khorasan, Ahmad Shah, who commanded a large body of cavalry in Nadir Shah's army, rode off eastward to conquer Afghanistan; and from that base he seized the whole Panjab between 1748 and 1751. Meanwhile the Marathas were spreading over Central India from the southwest like a devas-
