After the destruction of the Buddhas, 50 more caves were revealed. In 12 of the caves, wall paintings were discovered. In December 2004, an international team of researchers stated the wall paintings at Bamiyan were painted between the 5th and the 9th centuries, rather than the 6th to 8th centuries, citing their analysis of radioactive isotopes contained in straw fibers found beneath the paintings. It is believed that the paintings were done by artists travelling on the Silk Road, the trade route between China and the West.