Answer: They thought they could benefit from the area's warm climate and fertile soil.
The text starts with a comparison between Georgia and other places such as China and Palestine in terms of location. The comparison is meant to show that the weather and agricultural qualities of the region are likely to be similar, thus making it possible for Georgians to cultivate and produce similar goods to those in Eastern regions.
They did not believe they would be dependent on England because they thought Georgia could be very fruitful. They probably thought they would generate enough to be self-sufficient as well, but this is not stated as a major concern in the text. Finally, they do not mention any trade with Asia. They just talk about being able to supply England.