A vastly populated galaxy will always have people trying to gain control of it. The two biggest players in this galactic tug of war are the Galactic Empire and the Rebel Alliance. But don't be fooled into thinking that these two forces are the only ones interested in being the dominant force; as the Hutt cartel rules most of the Underworld, they too have an interest in seizing control of economic interests.
On most planets there are minor factions that try to keep to themselves while others desire planetary control, like the Tusken Raiders on Tatooine. Not all planets are controlled by a major faction, however; Lok is controlled by the famous smuggler Nym, and Dathomir is controlled by warring clans, the infamous Nightsisters and it's friendlier rival, the Singing Mountain Clan.