There are plenty of source materials to reconstruct the history of the Gupta period. They include literary, epigraphical and numismatic sources. The Puranas throw light on the royal genealogy of the Gupta kings. Contemporary literary works like the
Devichandraguptam and the Mudhrakshasam written by Visakadatta provide information regarding the rise of the Guptas. The Chinese traveler Fahien, who visited India during the reign of Chandragupta II, has left a valuable account of the social, economic and religious conditions of the Gupta empire.
Apart from these literary sources, there are inscriptions like the Meherauli Iron Pillar Inscription and the Allahabad Pillar inscription. The first refers to the achievements of Chandragupta I. The most important source for the reign of Samudragupta is the Allahabad Pillar inscription. It describes his personality and achievements. This inscription is engraved on an Asokan pillar. It is written in classical Sanskrit, using the Nagari script. It consists of 33 lines composed by Harisena. It describes the circumstances of Samudragupta's accession, his military campaigns in north India and the Deccan, his relationship with other contemporary rulers, and his accomplishments as a poet and scholar.
The coins issued by Gupta kings contain legends and figures. These coins provide interesting details about the titles and sacrifices performed by the Gupta monarchs.
The founder of the Gupta dynasty was Sri Gupta. He was succeeded by Ghatotkacha. These two were called Maharajas. Much information was not available about their rule. The next ruler was Chandragupta I and he was the first to be called Maharajadhiraja (the great king of kings). This title indicates his extensive conquests. He strengthened his position by a matrimonial alliance with the Licchavis. He married Kumaradevi, a princess of that family. This added to the power and prestige of the Gupta family. The Meherauli Iron Pillar inscription mentions his extensive conquests. Chandragupta I is considered to be the founder of the Gupta era which starts with his accession in A.D. 320.
Samudragupta was the greatest of the rulers of the Gupta dynasty. The Allahabad Pillar inscription provides a detailed account of his reign. It refers to three stages in his military campaign:
Against some rulers of North India
His famous Dakshinapatha expedition against South Indian rulers
A second campaign against some other rulers of North India.
In the first campaign Samudragupta defeated Achyuta and Nagasena. Achyuta was probably a Naga ruler. Nagasena belonged to the Kota family which was ruling over the upper Gangetic valley. They were defeated and their states were annexed. As a result of this short campaign, Samudragupta had gained complete mastery over the upper Gangetic valley.
Then Samudragupta marched against the South Indian monarchs. The Allahabad Pillar inscription mentions that Samudragupta defeated twelve rulers in his South Indian Expedition. They were Mahendra of Kosala, Vyaghraraja of Mahakanthara, Mantaraja of Kaurala, Mahendragiri of Pishtapura, Swamidatta of Kottura, Damana of Erandapalla, Vishnugupta of Kanchi, Nilaraja of Avamukta, Hastivarman of Vengi, Ugrasena of Palakka, Kubera of Devarashtra and Dhananjaya of Kushtalapura. Samudragupta's policy in South India was different. He did not destroy and annex those kingdoms. Instead, he defeated the rulers but gave them back their kingdoms. He only insisted on them to acknowledge his suzerainty.
The third stage of Samudragupta's campaign was to eliminate his remaining north Indian rivals. He fought against nine kings, uprooted them and annexed their territories. They were Rudradeva, Matila, Nagadatta, Chandravarman, Ganapathinaga, Nagasena, Achyuta, Nandin and Balavarman. Most of these rulers were members of the Naga family, then ruling over different parts of north India.
After these military victories, Samudragupta performed the asvamedha sacrifice. He issued gold and silver coins with the legend 'restorer of the asvamedha'. It is because of his military achievements Samudragupta was hailed as 'Indian Napoleon'.
Samudragupta was succeeded by his son Chandragupta II Vikramaditya. But according to some scholars, the immediate successor of Samudragupta was Ramagupta, the elder brother of Chandragupta II. But there is little historical proof for this. Chandragupta II inherited the military genius of his father and extended the Gupta Empire by his own conquests.
He achieved this by a judicious combination of the policy of diplomacy and warfare. Through matrimonial alliances he strengthened his political power. He married Kuberanaga, a Naga princess of central India. He gave his daughter Prabhavati in marriage to the Vakataka prince Rudrasena II. The political importance of this marriage lies in the fact that the Vakatakas occupied a geographically strategic position in the Deccan. This alliance served a useful purpose when Chandragupta-II undertook his campaign in western India against the Sakas.