If you wanted to get rich, you had to build roads first. Times might change, but that saying applied everywhere.
It was the same simple principle here: whenever an Imperial ship explored a new region, the first thing to do was find a place to set up a Star Gate. Light up the flight point first, then worry about the rest.
In the Imperium of Man, this kind of frontier-exploration work was usually handled by Rogue Traders. Only afterward would the Adeptus Mechanicus or even the Administratum send people to survey the region.
Though Rogue Traders had the word "trader" in their name, they weren't a bunch of thrill-seeking fools. They were officially recognized, armed organizations whose existence was recorded by the Imperium.
A small family might own only two or three merchant ships, while a powerful one could control several star systems. They held Rogue Trader charters bearing a drop of blood from the Emperor or even a Primarch, sailed Imperial Navy warships, and sometimes hired Space Marines as bodyguards.
In short, Rogue Traders weren't pushovers. They were the representatives of their respective Legions, and every family that had survived to this day had something unique about it. Their fighting spirit and resilience were enough to leave anyone in awe.
During the Great Crusade, the Legions conquered worlds so efficiently that Rogue Traders barely made a name for themselves. But things were very different now. With Guilliman's 500 Worlds of Ultramar setting the example, every Legion had begun its own grand farming enterprise.
The styles of these Rogue Traders varied widely with the customs of their Legions, but no matter how you looked at it, they were all quite fond of the Lord of Blacklight. Most of them were Blacklight Believers to some degree.
After all, when you were