People that came from a Vault that had many Gecks. The Vault was populated by ecologists and environmental activists (It's role in the experiments is not fully known). They creatued their own Vault City some where in the Midwest. The vault dwellers saw what man had done to the world. They dedicated themselves to saving the wasteland and making it green and finding Gecks. They are not as peaceful as they first appear. They take it upon themselves to re-educate the people of the wasteland. Those they can't reform to the ways of Mother nature they find other uses for them such as slaves, fertilizer and even food (everything gets recycled). They do see a use for technology and are advanced. They know how to use genetic engineering.
They send scouts out with four goals. To recruit people to their cause. To find other advanced groups and learn as much as they can. They are not above stealing or even killing to get information they want. Third is to map as much of the wasteland as they can. Last, to find more Gecks and geck related information.
They see most towns an settlements as blights. They destroy most that they come across and resettle thoses that are worthy.