The multitude of camels; rather, a multitude—a continual stream of caravans (Kay). These would be composed of merchants from Midian and Ephah, and would bring goods from Sheba. The Midianite caravans of camels are mentioned as early as the time of Jacob, when they carried "spicery and balm and myrrh" from the land of Gilead into Egypt (Genesis 37:25, Genesis 37:28, Genesis 37:36).
Ephah is a sub-tribe of Midian (Genesis 25:4). These nomads would visit the distant Sheba, in Happy Arabia, for purposes of trade, and would procure there gold and incense, which they would convey to Palestine.
The "Sheba" intended is doubtless that whose queen visited Solomon, and brought with her gold in abundance, and "of spices very great store, and precious stones" (1 Kings 10:10). The Egyptians appear to have called the kingdom of the Shebaim (Sabaeans) "Punt," and to have traded with it from a very early time, especially for frankincense.
The dromedaries; rather, the young camels, or the camel colts. All they from Sheba shall come; rather, they (i.e. the camels of Midian and Ephah) shall come all together from Sheba.