The term 'Panchnad' refers to the five rivers of Punjab, which are an integral part of the region's geography and history. These rivers are:
Given the options, the river that is not part of the Panchnad is 'The Luni'. The Luni River primarily flows through the Indian states of Rajasthan and Gujarat and is not associated with the geographical region of Punjab, which is characterized by the confluence of its five major rivers listed above.
Therefore, the correct answer is: The Luni.