Peshwa was not a Dynasty but prime ministers of Maratha Empire were known as peshwas. Balaji Vishwanath was the founder of peshwa dynasty. This is suitable according to your question. He was the sixth peshwa of Maratha Empire and first among their hereditary lineage of Peshwas. He belonged to the Chitpavan konkanasta brahmin hindu family, residing in Saswad village, near Satara.
The extension of Maratha Empire called Maratha Confederacy. The Confederacy was the ruling of the nobles called Peshwas. Next peshwa was Bajirao Ballal or Bajirao I who was the elder son of Sree mant Balaji Vishwanath Bhat. After the death of Sahuji, there was no efficient ruler, so the Peshwas took over the Empire, forming Maratha Confederacy.