In Mahabharata, five Kekaya princes were mentioned, who joined the Pandavas in Kurukshetra War. The eldest of them was described as a king and was known asVrihatkshatra. These Kekaya brothers were also banished from their kingdom by their own kinsmen, like the Pandavas who were bansished from their Kuru Kingdom, by their cousin brothers viz the Kauravas headed by Duryodhana. Thus these Kekaya brothers were circumstantially inclined to ally with the Pandavas. Besides this, the Kekaya brothers were sons of the sister of Kunti, the mother of Pandavas, making them cousins. In Kurukshetra War, the Kekaya brothers fought against their own kinsmen, viz the other Kekaya brothers who sided with Duryodhana.
http://en.wikipedia.org/wiki/Kekeya_Kingdom#Kekayas_in_Kurukshetra_War
http://en.wikipedia.org/wiki/Kekeya_Kingdom#Kekayas_in_Kurukshetra_War
