The Arab historian al-Hamdani wrote that Sanaʽa was walled by the Sabaeans under their ruler Sha'r Awtar, who also arguably built the Ghumdan Palace in the city. Because of its location, Sanaʽa has served as an urban center for the surrounding tribes of the region, and as a nucleus of regional trade in southern Arabia. It was positioned at the crossroad of two major ancient trade routes linking Ma'rib in the east to the Red Sea in the west.