The Sacrifice of Dragonkind explains why Basgiath was chosen for the location of the wards.

“Green dragons, especially those descending from the line of Cruaidhuaine, have an especially stable connection to magic, which some believe is a result of their more reasonable, defensive nature.”

“Many historians choose to ignore the sacrifices made by both humans and dragonkind to establish Navarre under the first wards in favor of praising the spirit of unification, but I would be remiss not to mention the losses suffered, both in terms of the ancestral hatching grounds of each dragon breed and the civilians who did not survive the continent-wide migration that resulted from the opening of Navarre’s borders…or those lost when we closed them.”