Adam Clarke on Isaiah 23:3

The seed of Sihor "The seed of the Nile" - The Nile is called here Shichor, as it is Jer 2:18, and 1Chr 13:5. It had this name from the blackness of its waters, charged with the mud which it brings down from Ethiopia when it overflows, Et viridem Aegyptum nigra fecundat arena; as it was called by the Greeks Melas, and by the Latins Melo, for the same reason. See Servius on the above line of Virgil, Georg. 4:291. It was called Siris by the Ethiopians, by some supposed to be the same with Shichor. Egypt by its extraordinary fertility, caused by the overflowing of the Nile supplied the neighboring nations with corn, by which branch of trade the Tyrians gained great wealth.