AISAR was a River-God of Tyrrhenia or Etruria (Tuscany) in central Italy.
The River Aisar merged with the Arnos near Pisa.
Strabo, Geography 5. 2. 5 (trans. Jones) (Greek geographer C1st B.C. to C1st A.D.) :
"Pisa [in Italia] is situated at the confluence of two rivers, the Arnos and the Ausar . . . And the following fable is told : when these Rivers first began to flow down from the mountains, and their course was being hindered by the natives for fear that they would unite in one stream and deluge the country, the Rivers promised not to deluge it and kept their pledge."
- Strabo, Geography - Greek Geography C1st B.C. - C1st A.D.