Editor’s Note: This is the first part of a series on Pakistan. While Pakistan’s boundaries encompass a large swath of land stretching from the peaks of the Himalayas to the Arabian Sea, the writ of the Pakistani state stops short of the country’s mountainous northwestern frontier. The strip of arable land that hugs the Indus River in Punjab province is the Pakistani heartland, where the bulk of the country’s population, industry and resources are concentrated. For Pakistan to survive as a modern nation-state, it must protect this core at all costs. But even in the best of circumstances, defending the Pakistani core and maintaining the integrity of the state are extraordinarily difficult tasks, mainly because of geography. The headwaters of the Indus River system are not even in Pakistan — the system actually begins in Indian-administered Kashmir.