The first Mishnah in Megillah discusses which days Megillah should be read and gives a reason why specific days Megillah should be read because the it would give time for the Villagers to come to the main City to hear the Megilah. If there is an obligation to be in a place where there is a Minyan, why are the Villagers living where they are without a Minyan? Furthermore, how could Rav Shimon Bar Yochai be ina cave without a Minyan? How did all the Gedolim in Europe who travelled from place to place do it without having a Minyan? The answer is , Halacha dictates that if you are in a town or within reasonable distance of a town that has a Minyan, one is obligated to attend. Otherwise there is no obligation.
