The Kshatrapa dynasty became very powerful with the accession of Nahapana to the throne. Ksatrapa Bhumaka was succeeded by him who flourished about the period 60 CE. Jain Works are unanimous in that Nahapana ruled Ujjain for 40 years while the inscriptions made by Ushavadata evince that Nahapana ruled for 46 years. Thus, Nahapana must have captured Ujjain in his 6th regnal year. Periplus of 60 CE evince that Nahapana was ruling Ujjain, thus fixing his regnal period from around 119 CE to 124 CE. Nahapana managed however to build a strong power base in the west, occupying the traditional base of Satavahanas in Western Maharasthra.
|“||Beyond the gulf of Baraca is that of Barygaza and the coast of the country of Ariaca, which is the beginning of the Kingdom of Nambanus and of all India. That part of it lying inland and adjoining Scythia is called Abiria, but the coast is called Syrastrene. It is a fertile country, yielding wheat and rice and sesame oil and clarified butter, cotton and the Indian cloths made therefrom, of the coarser sorts. Very many cattle are pastured there, and the men are of great stature and black in color. The metropolis of this country is Minnagara, from which much cotton cloth is brought down to Barygaza.||”|
|— Periplus 41|
He also established the Kshatrapa coinage, in a style derived from Indo-Greek coinage. The obverse of the coins consists of the profile of the ruler, within a legend in Greek. The reverse represents a thunderbolt and an arrow, within Brahmi and Kharoshthi legends.
Nahapana is mentioned as a donator in inscriptions of numerous Buddhist caves in northern India. The Nasik and Karle inscriptions refer to Nahapana's dynastic name (Kshaharata, for "Kshatrapa") but not to his ethnicity (Saka-Pahlava), which is known from other sources.
Nahapana had a son-in-law named Ushavadata (Sanskrit: Rishabhadatta), whose inscriptions were incised in the Pandu-lena caves near Nasik. Ushavadata was son of Dinika and had married Dakshamitra, daughter of Nahapana. According to the inscriptions, Ushavadata accomplished various charities and conquests on behalf of his father-in-law. He constructed rest-houses, gardens and tanks at Bharukachchha (Broach), Dashapura (Mandasor in Malva), Govardhana (near Nasik) and Shorparaga (Sopara in the Thana district). He also campaigned in the north under the orders of Nahapana to rescue the Uttamabhadras who had been attacked by the Malayas (Malavas). He excavated a cave (one of Pandavleni Caves) in the Trirashmi hill near Nasik and offered it to the Buddhist monks.
Overstrikes of Nahapana's coins by the powerful Satavahana king Gautamiputra Satakarni have been found in a Southern Gujarat hoard at Jogalthambi. However, it is not necessary that Gautamiputra Satakarni and Nahapana to be contemporaries since Satakarni mentions that the areas he has conquered were ruled by Ushavadata, rather than Nahapana. According to archaeologist James Burgess, there might have been an interval of as much as a century between the reigns of these two kings.
- "The mention of 'Nambanus' whom the scholars have identified as Nahapana in the Periplus of the Erythrean Sea would help us to solve the problem of Nahapana's time.", in "History of the Andhras" Archived March 13, 2007, at the Wayback Machine.
- quoted in "The Periplus of the Erythraean Sea: Travel and Trade in the Indian Ocean by a Merchant of the First Century". Fordham University. Retrieved 11 May 2013.
- Magarastra.gov.in Ancient Period Archived March 3, 2007, at the Wayback Machine.
- Burgess, James (1880). The Cave Temples of India. Cambridge University Press. pp. 266–268. ISBN 978-1-108-05552-9.
- Chattopadhyaya, Sudhakar (1974). Some Early Dynasties of South India. Motilal Banarsidass. p. 77. ISBN 978-81-208-2941-1.
- Students' Britannica India. 4. Encyclopædia Britannica. 2000. p. 375.
- R.C. Senior "Indo-Scythian coins and history" Vol IV, ISBN 0-9709268-6-3