Megadozer

is the homeland of the Giant Clan and Diane of the Seven Deadly Sins. It is somewhat over 300 miles North of Camelot.

Background
Megadozer is the place where the Giants are born and live when they are not making a commission. Diane fled from there as a child because of her hatred of fighting, but returned a while later after King erased her memories of their time together.

Istar arc
When Diane  forgot about the whole time spent with her comrades, because of Gowther's Lost World, she leaves Camelot to come back to her hometown.