The purpose of this study was to investigate the causes of and conflicts along the 2250 KM Durand line that separates two neighboring states. Although both countries are Muslim, their disputes are particularly difficult because Pashtuns, drug trafficking, and the Taliban administration are the two biggest problems in Kabul and Islamabad. Two close Muslim neighbors’, Pakistan and Afghanistan, have linguistic ties as well as deep historical, ethnic, cultural, and religious ties. Although Pakistan and Afghanistan share a strategic location and many other things in common, their relationship is marked by mistrust, suspicion, and bitter experiences for both parties. Since the beginning, Pakistan has had to deal with Afghanistan's hostility. All Afghan monarchs, with the exception of the Taliban's four-year rule, expressed varying degrees of hostility towards Pakistan. Conflict over the Duran Line, Pakistan's backing for the Taliban during the Soviet-Afghan War, Pakistan's involvement in the War on Terror, and the rise of cross-border extremism have all harmed relations between the two nations. This study's primary goal is to assess Pakistan-Afghanistan relations historically and to identify the biggest roadblocks to a harmonious and constructive relationship.