Boechari (1976 ) has discussed this subject in an article. He agrees with Van Bemmelen's idea of the eruption of Mount Merapi. He disagrees, however, on the period of the disaster. Van Bemmelen associates the disaster with the ”pralaya” which destroyed the palace of Dharmawangsa in 1016/1017. Boechari places it around 930, the time that the inscriptions came to an aprubt halt in Central Java.
We agree with van Bemmelen as regards the eruption of Mount Merapi, but with Buchari as regards the period of transfer of the keraton to East Java. There is a proof of this : the Candi Sambisari47) which is in the plains of Prambanan, was excavated in 1969 from about four meters of volcanic ashes. The style of the ornaments and statues are from the period of the Prambanan temple or a little later. There are also a few other indications that an eruption of Mount Merapi had covered whole areas with lava or ashes (observations by geologists).
When Mount Merapi erupts, fertile areas, villages, and roads can be destroyed in a minimum of time. Even now, when we drive to the Borobudur after an eruption we can see how roads and bridges have been damaged. Nowadays with modern equipment new roads and bridges can be easily rebuilt. But not so in the 10th century. The road connecting the capital, which was perhaps in the plains of Prambanan, with the busy trade ports on the north coast of Central Java was destroyed and remained so.
The existence of such a road is to be found in the inscription of Mantyasih which had to be protected by the patihs of Mantyasih. Boechari suggests that this is the road that connected the Kedu plains with the north coast via Parakan (Boechari 1976:9).
We suggest that, after the destruction of this road, the harbour princes, now independent from the suzerainty of the kings in the interior, were free to trade with Sriwijaya. They were on a friendly footing with the rulers of Sriwijaya, or to put it more strongly: they were still loyal to the Sailendras.
The kings, who were the successors of Sanjaya, could no longer enjoy the revenues of the seaborne trade. This was one reason that they had to transfer the center of power to East Java. Their presence there would not imply a heightened trade on the eastern islands. It is quite possible that the harbour princes of the north coast of Central Java prevented them from trading with these islands. They were the people who sent the commodities to Sriwijaya, which sent missions to China. The interruption in the trade with China lasted until 992 when a Chinese merchant arrived in China with three Javanese ambassadors and their retinue on board.
This first mission after more than a century seems to coincide with the agressive attitude by King Dharmawangsa towards Sriwijaya. The Ambassador from Sriwijaya who happened to be in China could not return to