The revenge motive arising from Scythian attacks on the Medes in Asia a century or so earlier hardly accounts for a Persian king attacking Scythians in Europe. The real intention of Darius was made clear by the building of a bridge across the Bosporus. Darius commemorated the bridge by erecting two columns of white stone with inscriptions in cuneiform and in Greek letters. Herodotus described the campaign from the Scythian point of view, which shows that he relied chiefly on Scythian informants. The existence of a satrapy in Europe, called 'Skudra', is known from Persian inscriptions. The name 'Skudra' was probably Phrygian for the homeland which the Phrygians had left in migrating to Asia. In cultural terms, Thrace looked not to Greece but to Scythia, Asia Minor and Persia. In the last decades of the sixth century large tombs with gifts of gold and silver vessels and jewellery, and sometimes bronze helmets and cuirasses, became much more frequent.