Genghis Khan (1162-1227), Mongolia’s great emperor, ruled over large parts of the world for a long period of time. He had, under his banner, nomadic tribes and desert people. For controlling, uniting and disciplining the variant people and ruling over them, he framed a conventional constitution named “Yasa” (Holy laws), which was comprised of primitive traditions, customs, laws and Genghis Khan’s own insights and decisions. Every subject was obliged to abide by the rules of the said constitution. “Pashtunwali” is the Comprehensive customary law of the way of life of Pashtuns. Pashtuns call their supreme morals, merits, actions, customs, civilization and values as “Pashtunwali”. Pashtuns are mandated to live their life according to “Pashtunwali”.Both Mongols and Pashtuns had their own distinct ways of life and conventional constitutions, which the Mongols called “Yasa” and the Pashtun’s “Pashtunwali”. For centuries, no amendment was made possible in both these constitutions. But it was only after they embraced Islam that we see some changes made in their conventional constitutions. Because the “Yasa” was to some extent, according to Islam while the Pashtunwali too was mostly according to Islam. So the followers of the two constitutions, therefore, did not find it hard to act upon the message of Islam. Therefore, the need of the hour is that both the conventional constitutions of Mongols and Pashtun be analyzed in Islamic perspective so as to find out what they shared with the teachings of Islam and where they differed. Furthermore, we shall be able to explore, through this research, the aspects that the Pashtuns and Mongols shared intellectually.