greek traders seem to have been meeting nomads in the district as early as the 7th century bc without a formal, permanent settlement. greek colonies had two kinds of origins, "apoikiai" of citizens from the mother city-state, and "emporia", which were strictly trading stations. founded late in the 3rd century bc, by merchant adventurers from miletus, tanais quickly developed into an "emporium" at the farthest northeastern extension of the hellenic cultural sphere. it was a natural post, first for the trade of the steppes reaching away eastwards in an unbroken grass sea to the altai, the scythian holy land, second for the trade of the black sea, ringed with greek-dominated ports and entrepots, and third for trade from the impenetrable north, with furs and slaves brought down the don. strabo mentions tanais in his "geography" (11.2.2).