"My name is Tito, licensed master-shipman of the ports of Argos. I am bound for Cush, to trade beads and silks and sugar and brass-hilted swords to the black kings for ivory, copra, copper ore, slaves and pearls." -- Robert E. Howard: "Queen of the Black Coast"
Hyborian kingdom situated southwest of Ophir, west of Koth and Shem, and south of Zingara -- where an Argossean panhandle juts westward.
Argos was a nation of paramount seafarers, with cosmopolitan cities along the coast. Its capital, Messantia, lay on the coast at the estuary of the Khorotas River. The most fertile region in Argos is the Khorotas River valley. The valley is filled with fruit orchards, farms, and oak forests where Argos' shipbuilding industry gets its wood.
The inland provinces were culturally rather backward. Along the Zingaran border were ghoul-haunted forests; south of these lay orchards and croplands.
The Argossean people were an amalgam of Zingaran and Shemite races. They were the best sailors in the Hyborian world -- according to everyone but the mariners of Zingara!
Argos was anciently a part of Acheron. It may have been the third of the Hyborian kingdoms to be established, after Nemedia and Aquilonia. Argos had a long-standing feud with Zingara, based on their maritime rivalry. Zingara essayed an incursion into Argos when Conan was a young man. The Argosseans under King Milo trounced King Ferdrugo's invaders soundly.
After Conan's time, the Aquilonian Empire annexed Argos. Still later, the Pictish hordes looted and burned the region. With the advance of the glaciers, Argos vanished beneath the sea.
References: Hyborian Age I-II, City of Skulls, Queen of the Black Coast, Snout in the Dark, Castle of Terror, Conan the Buccaneer, Red Nails, Hawks Over Shem, Treasure of Tranicos, Hour of the Dragon, Conan the Liberator, Conan the Guardian, et al.