The galaxy is home to very old stars, with the average age around 10 Billion Years. Due to this age, habitable planets are uncommon.
The galaxy has a very large proportion of dark matter ( It actually does ), which is so far unexplained. ( and, i mean, how do i write about an unexplained material? )
After the discovery of Wormholes, visits were attempted. after extensive exploration, almost no habitable planets were identified. However, a planet in isolation of other habited planets is not very desirable. Due to this, the population of the entire galaxy is less than 1 million, mainly populated by merchants ( as certain wormholes pass through here ) and pirates, due to the wormholes and the lack of much opposition.