From publisher blurb:
Everything the weary traveller might need can be found at Oasis Al-Velle. A central location in the desert, the Oasis also acts as a major trade center between the desert and the more fertile lands beyond. But there are those who want to use the Oasis for their own purposes, or take complete conrol of it - and all of the water and trade it possesses.
AT-6 can be a built-up oasis in any campaign world, or used with other Sevich desert campaign modules to create an integrated campaign. Modules set in and around the oasis include ONA 21 though ONA 24. Played together, these modules make the AT-6 Adventure Tome. This Adventure Tome is the culmination of the Sevich Desert campaign, and can be played with AT-4 The Port of Dakhalla Adventure Tome and AT-5 Exterris Adventure Tome.