From the Mongoose website:
The Trojan Reaches awaits your exploration in this huge poster map, featuring every system, trade link and starbase in the sector. Beautifully illustrated in full colour, this map is the second in a series that will allow you to explore the entire Third Imperium and beyond, joining posters together to form one gigantic map!
The Trojan Reaches are fully detailed and explored in Alien Module 1: Aslan.
Includes a full key to aid navigation.