Kshudrakas are a Hindu community and they fiercely opposed Greeks in ancient India. The name Kshudraka first occurs in Ganapatha of Panini (IV.2.45). R.G. Bhandarkar identified the Kshudrakas with the Oxydrakai of the Greek historians.
Megasthenes and Arrian tell us that the Persians in the 6th century BD had ‘hired mercenary troops from India, namely the Hydrakes (Oxydrakai = Kshudrakas).
Evidently, the Kshudrakas had achieved an international reputation as extraordinary people at that time.
Even in the 4th century BC, they were one of the most powerful republican states that Alexander met during his retreat down the Indus.
They lived to the northeast of the Malloi (Malava), who dealt on the Hyadepes (Jhelum), below its confluence with the Chenab.
Kshudrakas and another group of warriors referred to as Maloi had formed a league. They had a very strong army.
As per McCrindle the Macedonians lost their heart at the prospect of meeting this army. The fear of the Macedonian soldiers was well justified, as is attested to by the fact that in the siege of an important fortified city Alexander nearly lost his life.
The Greek writers tell us that when the stronghold fell, the infuriated Macedonian soldiers massacred all the inhabitants, sparing neither women nor children. But Patanjali refutes this claim of Greek writers and states that the Kshudrakas alone were victorious.
The description of Greek writers of an uncommon hospitality to the 100 ambassadors of Kshudrakas by Alexander indicates that some sort of respectable treaty took place between the two.
The Mahabharata and the Puranas also mention the Kshudrakas. It seems that, like many other tribes and communities of the region, they also move to northern Rajasthan under alien pressure and issued their republican coins during the 2nd century BC.
Source – Encyclopedia of Hinduism Volume VI page 152 - IHRF