Tartessus (as Asshur became Athur, Bashan, Batanoea), a Phoenician city S. of Spain; the portion of Spain known to the Hebrew (Psalm 72:10). "The kings of Tarshish ... kings of Sheba," i.e. the wealthy Tarshish in the far W. and Sheba in the S.E. Tarshish was a dependency of Phoenician Tyre. Isaiah 23:6; Isaiah 23:10 ("pass through thy land as a river, O daughter of Tarshish," i.e. Tartessus and its inhabitants would now that Tyre's strength was disabled pour forth as waters, no longer kept working mines for the parent city), 14,18; Ezekiel 26:15; Ezekiel 26:18; Ezekiel 27:12. "Tarshish was thy (Tyre's) merchant ... with silver, iron, tin, and lead, they traded in thy fairs."
Tarshish was famed for various metals exported to Tyre; most of them were drawn from Spain and Portugal, tin possibly from Cornwall or from Lusitania or Portugal. "Ships of Tarshish" are mentioned often: Psalm 48:7, "Thou brakest the ships of Tarshish with an east wind," alluding with undesigned coincidence to the event recorded 2 Chronicles 20:36-37; "Jehoshaphat joined himself with Ahaziah king of Israel to make ships to go to Tarshish ... in Ezion Gaber ... because ... the Lord hath broken thy works," i.e. wrecked thy ships. The ships of Tarshish built at Ezion Geber on the Elanitic gulf of the Red Sea (1 Kings 22:48) were intended by Jehoshaphat to trade with Africa and India; but a copyist in 2 Chronicles 20:36 makes them go to Tarshish.
It is possible they were carried across the land to the Mediterranean, but more likely that "ships of Tarshish" mean large vessels, as our phrase "East Indiamen" does not imply the destination but the size; the copyist mistook the phrase for the destination. So in 1 Kings 9:26; 1 Kings 10:22; 2 Chronicles 9:21; the "peacocks" point to India, for southern Asia and the isles of the eastern archipelago are their native home. The names too are of Sanskrit etymology, tukki, related to Tamil Iota, "the tailed bird," i.e. peacock. So "apes," kaph, related to Sanskrit kapi. The Greeks received the peacock from Persia, as the Greek taos is the Persian tans. Strabo makes the Boetis or Guadalquivir (great stream) be called Tartessus. An island, a town, and a region bore the name. (On Genesis 10:4, which Rawlinson refers to Tarsus, at the close.) (See TARSUS.)
Fausset, Andrew Robert M.A., D.D., "Definition for 'tarshish' Fausset's Bible Dictionary".