The keris originated in Java. No precise date can be given. However, it would be safe to say that the proto-keris was developed between the 9th century AD and the 14th century AD.
Most scholars (albeit western) put the date to sometime in the 12th century AD.
The basis of this is that the earlist representation of a true keris in
temple carvings appear on the 14th century Shiva Temple of Candi Penataran.
In this relief from the Shiva Temple at Candi Penataran someone is executed
with a keris.
Most of the buildings in the Candi Penataran complex, which is situated in the neighbourhood of Blitar in the eastern part of Java, are build in the Golden Age of the Majapahit Period. Dates have been found which correspondent with AD: 1197 to 1454.
The best known representation of a keris is the mysterious 15th century
relief from Candi Sukuh, at Mount Lawu in Central Java. Dated incriptions
discovered at Candi Sukuh range from AD: 1416 to 1456.
It presumably represents the divine weapon smith Bima, an incarnation of
the god Shiva, who is forging a keris with his fist in a workshop. The keris
is placed on some kind of table or ledge. In the background of the workshop
there are several instruments and ceremonial weapons under which some
kerises.
In the center of the picture is a naked, bulky man with an elephant's head,
who is probably Shiva's second son Ganesha with a dog in his hand, helping
Bima to overcome all difficulties.
At the right side of the picture Bima's assistant, some sources indicate this
is a representation of Bima as well - others say it is his wife, is fueling the
fire with two vertical positioned piston-bellows, commonly used in Indonesia.
Blacksmiths and especially kerismakers have been highly respected in Indonesia,
but what relationship this scene bore to the ceremonies once conducted at
Candi Sukuh is unknown.
The keris would have taken time to evolve into its final form and the experts estimate that it would have taken about 100 to 200 years. Hence the proto-keris must have appeared sometime in the 12 century. It is unlikely that the keris was invented before the 9th century. There are no representations of kerises in the temple carvings of Borobudur and Prambanan which date from that time. A weapon of such spiritual and cultural significance would never have been left out of the carvings if it had existed at that time.
The Malays and the Bugis claim that the keris originated in their culture. However, it is clear that the keris is a Javanese invention. None of the non-Javanese myths or heroic legends concerning the keris predates Javanese myths, neither physical evidence has been found to support these theories.
In its most basic definition a keris is a double egded dagger with an
asymmetrical base of the blade and a tang which fits into a hilt. The hilt
usually represents the abstract form of something or someone.
The front side of the blade goes rather straight down while the backside
ends in a long, a little bit upward bending, tailshape tip.
Only the oldest kerises differ from this definition in the way that they have
a hilt which is forged together with the blade and have a shape of a man.
Bima in his workshop