The Yavana Era, or Yona (Prakrit: Yoṇaṇa vaṣaye) was a computational era used in the Indian subcontinent from the 2nd century BCE for several centuries thereafter, probably starting in 174 BCE. It was initially thought that the era started around 180-170 BCE, and corresponded to accession to the Greco-Bactrian throne of Eucratides, who solidified Hellenic presence in the Northern regions of India. The Greeks in India flourished under the reign of the illustrious, Menander - greatest of the Yavana rulers, who campaigned as far as Pataliputra in Eastern India. It is now equated with the formerly theorized "Old Śaka era".
Harry Falk and others have suggested that the Yavana era actually started in 174 BCE, based on a reevaluation of the Azes era which is now thought to have started in 47/46 BCE. The exact historical event corresponding to the creation of this Yavana era is uncertain, but it may mark the alliance of Antimachos I and Apollodotus I in toppling Agathokles, thereby creating a unified realm north and south of the Hindu-Kush.
