Antique historians were accurate enough to let us reconstitute the Danube Delta’s territory. Almost all sources agree that it began as a gulf, and changed into a lagoon before becoming a delta. According to these theories, the Delta was born as a bay of the Black Sea, and was cut off from the rest of the sea by a narrow sand bank, which transformed its western side into a lagoon. The predominant winds from the north-east caused high waves which built the sandbanks of Letea and Caraorman. Eventually, the sea closed off the lagoons, which were filled by the river and more sand. This process is continuing all the time, gradually pushing the Danube Delta into the sea.
The first historical information about the Danube Delta comes from the Greek historian, Herodotus, "the father of the history", who describes how Darius's Persian fleet entered the Delta after he had stayed in Histria between 515-513 BC. In the 3rd-2nd centuries BC, Polibius describes a place with sand banks that enclosed islands. This idea has been expressed by later Classical authors such as Pliny the Elder, Ptolemy and others.
