In 558, Khosrau I, Shah of Sassanid Persia, allied with the Göktürks to defeat the Hephthalites. The campaign was successful and the region north of the Oxus went to the Turks and the south came under Sassanid rule. However, in the 580's, the Turks once again commenced with their raids on the Silk Road and in 588, the Hephthalites, who were now part of the Western Turkic Khaganate, invaded the empire once more. It is reputed that an arrow shot by Bahram killed the Eastern Turkic Khagan, Bagha/Yabghu Qaghan, known as Ch'u-lo-hou by the Chinese .