Jasir is responsible for many of the survivors within the Countryside, his farm is the first safe zone Kyle Crane finds when he enters the area. In addition to the safe zone Jasir is also one of the central characters with the story quests for The Following as well as a number of side quests and diversions such as collecting Bolter livers and finding missing survivors.
After you find Tolga and Fatin, Jasir gives you a Military keycard. It is useful to access crates in military outposts across the Countryside. These crates contain weapons and blueprints to create parts for your buggy.