Yavana era

The Yavana Era, Yona Era or Yonana was a computational era used in the Indian subcontinent from the 2nd century BCE for several centuries thereafter. It is thought that the era started around 186 BCE, and corresponds to accession to the Greco-Bactrian throne of Demetrius, who is said to have initiated the Indo-Greek conquest of parts of Northwestern South Asia.

The creation of specific eras is a well-known phenomenon marking great dynastical events, such as the Seleucid era (starting in 312 BCE, with the return of Seleucus to Babylon), the Arsacid Era in Parthia (starting in 248/7), BCE), the Azes era in Gandhara (starting in 58/7), and the Kanishka era, when he established his empire in 127 CE.

Although Greco-Bactrian or Indo-Greek kings generally did not put dates on their coins, some of them Plato (circa 140 BCE) and Heliocles uncharacteristically do so. Some of the coins of Plato have inscriptions such as MZ, MT, MN which can be interpreted as dates in the Greek numerals system using the Yavana era which started around 186 BCE. In that case Plato ruled around 140 BCE. This matches the dating given by numismatician Bopearachchi, who places Plato between 145–140 BCE, since his coins are not found in the ruins of Ai Khanoum, a Bactrian city which was destroyed during the reign of Eucratides.

A recently discovered reliquary (published by Salomon in 2005) from Bajaur gives a triple dating which allows to clarify the relationship between several eras: it is dated to the 27th regnal year of Vijayamitra, a king of the Indo-Scythian Apraca, the 73rd years of the Azes era, and the 201st year of the Greeks (Yonanas or Ionians).

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