The Sattavahanas who are mentioned in the Puranas as the Andhra were the original inhabitants of Western Deccan. They however extended their sway over Eastern Deccan in the later years. The founder of the Sattavahana dynasty according to Puranas was Simuka who ousted the last Kanva king Susharman from the throne and established the dominion of the Sattavahanas. Since the ascension of Simuka to the throne for the next half-century, the Sattavahanas witnessed a series of decline owing to the Scythian invasion. But the Sattavahanas had experienced an incredible recovery under Gautamiputra Satakarni, the celebrated king of the Sattavahana Dynasty. He is also regarded the greatest of the Sattavahanas since his prosperity even excelled his predecessors. The exploits and achievements of Gautamiputra Satakarni were commemorated in the Nasik Prasasti, incised 20 years after the death of Gautamiputra by his mother Devi Gautami Balasri. Another important source about the reign of Gautamiputra Satakarni is the Nasik Prasasti.
The time period of Gautamiputra`s reign is a controversial subject and till date historians have failed to provide authentic information about that. Satakarni was the contemporary of Saka Kshatrapas, Nahapana and also defeated him in the eighteenth year of his reign. However Gautamiputra ruled till 130 A.D.
Gautamiputra Satakarni was described in the Nasik Prasasti as "Saka-Yavana Pallava Nisudana", the destroyer of the Sakas, Pahlavas and the Yavanas. The first sixteen years of his reign was devoted to the great preparation of the struggle against the Saka power under Nahapana. The coins of Nahapana engraved by the name of Gautamiputra, testifies his success against the Sakas. Nahapana had seized the Western Deccan from Sattavahanas. To take avenge Gautamiputra carried out a valiant struggle against the Sakas for two long years and finally killed Saka chief Nahapana and his governor Rishavadatta. The legend of the Saka-Sattavahana struggle during Gautamiputra is also known from a gatha in Nirukti. Nahapana defended his capital Brigukachchha from the Sattavahana invasion for two years but the accumulated wealth being exhausted, Nahapana became weak, defeated and finally was killed. Gautamiputra later uprooted the Yavanas and the Pahlavas from Deccan. Gautamiputra not only recovered his paternal land Maharashtra, the original homeland of the Sattavahanas, but also annexed the Saka kingdom in Gujarat, Berar, Saurashtra, Malwa and North Konkan.
The overthrow of the Sakas by Gautamiputra constituted the Sattavahanas as a formidable power in South. The idea of Digvijay began to haunt the Gautamiputra`s vision. From the Nasik Prasasti it is known that apart from the countries conquered from Nahapana, Gautamiputra extended his sway over the districts watered by the rivers of Rishika, Godavari and also the regions of Hyderabad and Berar. The conquests of Satakarni are known from the Nasik Prasasti. The territories conquered by Gautamiputra include Asika or Maharashtra, Muluka or northern Maharashtra, Surutha or Kathiawar, Kukura or Western Rajputana, Anupa or Narmada Valley, Vidarbha or Berar, Akara, Avanti or western Malwa, Aparanta or Konkan. The Nasik Prasasti also delineated that Gautamiputra was the master of the extensive land lying to the south of the Vindhya Mountain, extending from the Western Ghats to the Eastern Ghats and also included the Travancore region. However there is still a keen controversy among the historians whether the region of Andhra, the second home of the Sattavahanas and Southern Kosala were part of Gautamiputra`s territory.
The mighty conqueror Gautamiputra Satakarni also earned enough prosperity as an able and benevolent ruler. As a ruler Gautamiputra had a strong sense of public duty. To stabilise a strong administrative establishment he introduced twin foundations of Sastric Laws and humanism, on which his administration was based. He emphasised on the taxation system and levied taxes in conformity with justice. He worked for the well-being and upliftment of the poor and the downtrodden section of his Empire. As a king he witnessed the ill effects of narrow casteism, which had crept up in the society during the contemporary era. Hence he was a great patron and a promoter of Varnasrama dharma. At the same time he stopped the growth of sub castes due to the intermingling of four social orders. But Dr. Gopalachariya however thinks that sub-castes existed during that period. According to him, due to the multiplication of vocations, it was not practically possible for Gautamiputra to stop the growth of sub-castes. A sophisticated and learned king, Gautamiputra Satakarni was a staunch Brahmanist but he was benign to other religious sects also.
Such a tough and powerful king like Gautamiputra Satakarni towards the end of his reign suffered overthrows in Kardamaka Sakas. They snatched away most of the districts conquered by Gautamiputra from Nahapana, the king of the Kshatrapa Sakas. After the fall of the Kshatrapa Sakas, a sister branch of Kshatrapas, the Kardamakas emerged. The Geography of Ptolemy and the Girnar inscription of Rudramana also corroborate the fact.
Gautamiputra Satakarni the illustrious ruler of the Sattavahana Dynasty was successful in unifying the major parts of India under the authority of the Sattavahana Empire. Gautamiputra was considered the destroyer of the Sakas, Pahlavas and the Yavanas. Under Gautamiputra, the Sattavahana Empire attained a successful recovery and thriving prosperity. Being a benevolent ruler Gautamiputra was tolerant towards the other religious groups and introduced administrative reforms for the successful administration of the vast Empire. Gautamiputra Satakarni, hence can be regarded the greatest among the Sattavahanas.