The Ongin inscription was discovered in 1891 in Mongolia near the Ongi River, 160 km south of the Orkhon inscriptions and 402 km south-west of the Tonyukuk inscriptions. It was erected in honor of El Etmish Yabgu and written in Yenisey script. Line 12 makes it clear that the author of the inscription erected a memorial to his father. According to Gerard Clauson, it must have been erected between 716 and 735, during the reign of Bilge Qaghan. According to Ercilasun it was erected in 719 or 720.