The Persian infantry used in the invasion were a heterogeneous group drawn from across the empire. However, according to Herodotus, there was at least a general conformity in the type of armour and style of fighting.[170] The troops were, generally speaking, armed with a bow, 'short spear' and sword, carried a wicker shield, and wore at most a leather jerkin.[170][171] The one exception to this may have been the ethnic Persian troops, who may have worn a corslet of scaled armour.[170] Some of the contingents may have been armed somewhat differently;[170] for instance, the Saka were renowned axemen.[172] The 'elite' contingents of the Persian infantry seem to have been the ethnic Persians, Medians, Cissians and the Saka.[170] The foremost of the infantry were the royal guards, the Immortals, although they were still armed in the aforementioned style.[170][173] Cavalry was provided by the Persians, Bactrians, Medes, Cissians and Saka; most of these probably fought as lightly armed missile cavalry.[170][174] The style of fighting used by the Persians was probably to stand off from an enemy, using their bows (or equivalent) to wear down the enemy before closing in to deliver the coup de grace with spear and sword.[170]