If you use your godhand to place a boulder in the midst of one of the villages worshiping you, the villagers will start praying and dancing and chanting and whatnot around the boulder. After a long enough time with the villagers charging the bolder, it would radiate with your divine presence. At this point, it is a ready "artifact".

Artifacts don't expand you influence zone directly, but they do a really good job of getting non-believer villagers to start worshiping you, which does extend your influence in a major way.