German security officials estimate the membership of the hard-line Kurdish Workers Party at around 7,500, drawing on a much wider network of sympathizers.
The area also serves as a base for a variety of terrorist groups, including the Kurdish Workers Party and the Japanese Red Army.
The four were convicted of links to the Kurdish Workers Party; a hearing on their appeal is set for July 8.
The civilians are caught in the middle, suffering under the hard-line separatists of the Kurdish Workers Party but mostly under the security forces.
They also say that young men, who they believe belong to the Kurdish Workers Party, are spending time in the camp organizing meetings.
For the last few years, Turkey has been fighting its own campaign against Soviet-backed dissidents of the Kurdish Workers Party.
The Kurdish Workers Party says it is fighting for a separatist state among eastern Turkey's eight million Kurds.
Turkey is battling its own Kurdish guerrillas, who fight for autonomy under the banner of the Kurdish Workers Party.
The Kurdish Workers Party itself has a reputation for brutality, and many Western governments say it is a terrorist group.
Finding official spokesmen for the Kurdish Workers Party is all but impossible.