What was the boundary between the Delhi Sultan and Mongols during the period of Alauddin Khiliji after 1306 A.D. ?

Correct answer: C (Indus). After the Mongol invasions of 1303 and 1305-06, Alauddin Khalji's north-western frontier was fixed along the Indus. Ghazi Malik (later Ghiyas-ud-din Tughluq), as warden of the marches at Dipalpur, held the line and kept the Mongols on the western bank of the Indus.

• Beas (A): This river lies well inside the Punjab plains. It was never the outer limit with the Mongols, and the Sultanate's defensive posts were placed further west.
• Ravi (B): Also inside the Punjab, with Lahore and the Ravi zone as internal defence points rather than the frontier with Chagatai or Il-Khanid forces.
• Sultaj (D): This is a misspelling of Sutlej, which is a distractor. The Sutlej marked no Mongol boundary in this period.

The core concept is frontier defence (the warden of marches system) and the Sultanate's military response to the Mongol threat, which is a useful link to Mains questions on the Khalji military administration and its limits.

Trap: Aspirants pick the river that lies nearest to Delhi or the Punjab cities (Beas or Ravi), forgetting that the frontier was the Indus itself.