The four, all from Bihar, were arrested yesterday from Jitpur Bazaar of Parsa district in southern Nepal.
They have been identified as Jairam Mukhiya, 45, Ram Ayodhya Mukhiya, 41, Birendra Mukhiya, 60 and Wasar Mukhiya, 40.
The police arrested them as they were trying to run away with 18.2 kgs of hashish, according to Nepal Police.
During their interrogation, they told the police that they were just the porters and not the suppliers or dealers.
The police is investigating the matter.