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.[1]: 177 It was erected in honor of El Etmish Yabgu. Line 12 makes it clear that the author of the inscription erected a memorial to his father.[1]: 183 According to Gerard Clauson, it must have been erected between 716 and 735, during the reign of Bilge Qaghan.[1]: 191 According to Ercilasun it was erected in 719 or 720.[2]