Though dry regions may never be as densely populated as those near water, which of the following has led to increased populations in dry areas?

yes based on alexanders actions he deserved the title of "the great". his empire covered about 3,000 miles and he was able to establish the empire over a 13 year period of time. he was able to conquer many different places. he also defeated the persians. he conquered egypt and developed a city and named it after himself.

less available tax revenue

this basically means that when they get money from taxes wirth having a lower gdp they get less then what others have with a higher gdp