The Magadha Kingdom was established by King Jarasandha who was, as it stated in the Puranas, a king of Brihadrathas dynasty, one of the descendants of eponymical Puru. Jarasandha appears in the Mahabharatha as the “Magadhan Emperor who rules all India” and meets with an unceremonious ending. Jarasandha was the greatest among them during epic times. His capital was Rajagriha or Rajgir is now a modern hill resort in Bihar. Jarasandha’s continuous assault on the Yadava kingdom of Surasena resulted in their withdrawal from central India to western India. Jarasandha was a threat not only for Yadavas but also for Kurus. Pandava Bhima killed him in a mace dual aided by the intelligence of Vasudeva Krishna. Thus, Yudhisthira, the Pandava King, could complete his campaign of bring the whole of India in to his empire. Jarasandha had friendly relations with Chedi king Shishupala, Kuru king Duryodhana and Anga king Karna. His descendants, according to the Vayu Purana, ruled Magadha for 1000 years followed by the Pradyota dynasty which ruled for 138 years. However, no sufficient evidence to prove the historicity of this claim. However, these rulers are mentioned in the Hindu texts, Buddhist texts and Jaina texts.
Pradyota dynasty succeeded the Brihadrathas dynasty in Magadha. According to the Vayu Purana, Pradyotas ruled Magadha for 138 years from 799-684 BC. Palaka, the son of the Avanti king Pradyota, conquered Kaushambi, making the kingdom powerful.
Source : Wikepedia