This is the famous Forge Scene Stele located at Candi Sukuh, on the slopes of Mount Lawu,
in Central Java.
Candi Sukuh was built in the 15th. Century. A candra sangkala date at the entrance is read
as "Gapura bhuto aban wong" which translates as "Arch giant swallow human".
Read according to the candra sangkala, the Javanese symbolic numeral system, this gives a
date of 1359 in the Javanese calendar, or 1437AD.
This scene is important to the study of keris because it gives a definite time frame for the
existence of the keris. If you look at the wall behind the smith you will see various items
manufactured in the forge, including keris.
There are other monumental depictions of the keris at Candi Sukuh, one showing the form
of wrongko that we would now call a sandang walikat style wrongko.
These representations of the keris at Candi Sukuh establish beyond doubt that by the year
1437 the keris had already achieved a place in Javanese culture.
More about the early development of the keris can be read by using this link:-