Aria (Greek: Ἀρ(ε)ία Ar(e)ia, Latin Aria, representing Old Persian. Haraiva, Avestan Haraeuua), inhabitants: Arians (Latin: Arii, Greek: Ἄρ(ε)ιοι/Ar(e)ioi), name of a region in the eastern part of the Persian empire, several times confused with Arianē in the classical sources.

Aria was an Old Persian satrapy, which enclosed chiefly the valley of the Hari River (Greek Ἄρ(ε)ιος, this being eponymous to the whole land according to Arrian) and which in antiquity was considered as particularly fertile and, above all, rich in wine. The region of Aria was separated by mountain ranges from the Paropamisadae in the east, Parthia in the west and Margiana and Hyrcania in the north, while a desert separated it from Carmania and Drangiana in the south. It is described in a very detailed manner by Ptolemy and Strabo and corresponds, according to that, almost to the Herat Province of today's Afghanistan. In this sense the term is used correctly by some writers, e.g. Herodotus (3.93.3, where the Areioi are mentioned together with the Parthians, Chorasmians, and Sogdians); Diodorus (17.105.7; 18.39.6); Strabo (2.1.14; 11.10.1, cf. also 11.8.1 and 8; 15.2.8 and 9); Arrian (Anabasis 3.25.1); Pomponius Mela (1.12, where we read that “nearest to India is Ariane, then Aria”).

An aria (Italian for air; plural: arie or arias in common usage) in music was originally any expressive melody, usually, but not always, performed by a singer. The term is now used almost exclusively to describe a self-contained piece for one voice usually with orchestral accompaniment. Perhaps the most common context for arias is opera, although there are many arias that form movements of oratorios and cantatas. Composers also wrote concert arias, which are not part of any larger work, such as "Ah perfido" by Beethoven, and a number of concert arias by Mozart, such as "Conservati fedele".

The aria first appeared in the 14th century when it signified a manner or style of singing or playing. Aria could also mean a melodic scheme (motif) or pattern for singing a poetic pattern, such as a sonnet. It was also attached to instrumental music, though this is no longer the case. Over time, arias evolved from simple melodies into a structured form. In the 17th century, the aria was written in ternary form (A–B–A); these arias were known as da capo arias. The aria later "invaded" the opera repertoire with its many sub-species (Aria cantabile, Aria agitata, Aria di bravura, and so on). By the mid-19th century, many operas became a sequence of arias, reducing the space left for recitative, while other operas (for instance those by Wagner) were entirely through-composed, with no section being readily identifiable as a self-contained aria.