They successfully managed to survive in a hostile environment by establishing strongholds within enemy territory. They would secretly gain the support of the population around a strategic fortification, infitrate the fort, then convert it to one of their own. They did not have a contiguous territory, but had a series of strategic "islands"
within the territory of more powerful kingdoms, and they used these to provide sanctuary and support to other Naziris.
Since their records were burned, much of what has come down about them is folklore and rumor. However, a central theme in all the tradition is their exceptional skill at covert operations and assasination. One story has a Hashashin sneaking into Saladin's camp and placing a dagger on his chest as he slept.
They often struck in public, feeding their legend, and the power of the legend combined with the contemporary belief in their mystical powers was often all they needed to maintain the tenuous position of their minority people. They took contract work as assasins, and accounts of the Crusades relate how European leaders used them against other Crusader rivals.
In The Templar Concordat, this period is when the Templars and the Hashashin first began their long battle.