The name "Illyrians," as applied by the ancient Greeks to The Illyrians (Ancient Greek: , Illyrioi; Latin: Illyrii or Illyri) were a group of Indo-European tribes in antiquity, who inhabited part of the western Balkans. The territory the Illyrians inhabited came to be known as Illyria to Greek and Roman authors, who identified a territory that corresponds to Serbia, Croatia, Bosnia and Herzegovina, Slovenia, Montenegro, Kosovo[a] and most of central and northern Albania, between the Adriatic Sea in the west, the Drava river in the north, the Morava river in the east and the mouth of the Aoos river in the south. The first account of Illyrian peoples comes from the Periplus of Pseudo-Scylax, an ancient Greek text of the middle of the 4th century BC that describes coastal passages in the Mediterranean their northern neighbors, may have referred to a broad, ill-defined group of peoples.