MYA

MYA is an abbreviation of Millions of Years Ago, a common block unit of time in Generation 1 Transformers series. Event timelines in 2005's Transformers: The Ultimate Guide were organized in MYA's.

The backstories of the 1984 Cartoon and the Dreamwave comic were both structured with major events occurring at 1 million year epochs.

Note: The MYA 'unit' is used by fans and guidebooks; it does not exist within the fiction.

From Teletraan I: The Transformers Wiki, a Wikia wiki.