‘And their dwelling was from Mesha as you go towards Sephar, the mountain of the East.'
Mesha may connect with Massa in northern Arabia. Massa was the seventh of the twelve princes of Ishmael according to Genesis 25:14, demonstrating Arabian connections for the name, and may be identified with the Masa who paid tribute to Tiglath Pileser III. Sephar can possibly be connected with the coastal town Zafar in the kingdom of Hadramaut. This is possible but by no means certain, especially in view of the z instead of s.
“As you go towards -” essentially meaning ‘in the direction of'. This would seem to link the ‘sons' together as covering one large area in Arabia.