The earliest known users of the era are the Western Satraps, the Shaka (Indo-Scythian) rulers of Ujjain. From the reign of Rudrasimha I (178–197), they recorded the date of minting of their coins in the Shaka era, usually written on the obverse behind the king's head in Brahmi numerals.Rapson, "A Catalogue of Indian coins in the British Museum. Andhras etc." p. CCVIII
