Judge Vikas Kumar also imposed a fine of Rs 10,000 on each of them.
In June 2006, three brothers Bharose, Tulsi, Naresh along with Ram Avatar, Prakash and Ram Babu had killed Mohan over a petty dispute in Akbarpur village.
Mohan's brother Manohar Yadav had lodged an FIR against the six persons.
After hearing both the parties, the judge held all the accused guilty.