'Illyria' was the ancient name given to the territory inhabited by Illyrians off the eastern coast of what sea?

The Illyrians (Ancient Greek: Ἰλλυριοί, Illyrioi; Latin: Illyrii or Illyri) were a group of Indo-European tribes in antiquity, who inhabited part of the western Balkans and the south-eastern coasts of the Italian peninsula (Messapia). The territory the Illyrians inhabited came to be known as Illyria to Greek and Roman authors, who identified a territory that corresponds to Croatia, Bosnia and Herzegovina, Slovenia, Montenegro, part of Serbia and most of Albania. This territory was from the east coast of the Adriatic Sea to 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.