Rajputra is found in the Vedas, the Ramayana, and the Mahabharata. It has been used by Panini. The word Kshatriya was initially used for the community of warriors and rulers. After the passage of much time there were many Kshatriyas. Some of them left their traditional occupation. Some were still rulers and warriors. As a custom these kings married only with the daughters of kings. They were abundant in India. It is very clear from the Puranas, Ramayana, Mahabharata, Prithviraj Raso, Akbarnama, and present genealogy that they intermarried with the royal families only. The rule of primogeniture allowed only the eldest male offspring of a king to succeed him. The rest were known as Rajputras. The word Rajput is claimed to be a corruption of Rajputra. Gradually it became a jati within the Kshatriya or warrior caste, however the Rajputs are often considered the elite of the Kshatriyas - at least by their own members.
The traditional occupations of the Rajputs is military service and at times agriculture. However, due to their natural ability in warfare and their discipline, this would give them opportunities to rise through the ranks and eventually become rulers or at least hold high positions in office.
The concept of the Raja-putra, or "son of a king," is mentioned in Vedic literature. Rajput, a shortened version of Raja-putra, is a name that has come to be associated with specific clans that would gain political importance in a given region. Because of the fluid social structure in early medieval India, a tribe could gain or lose its status based on its political importance, its occupation, and its survival or extinction. Many tribes over the course of time became extinct because of war, or relocated to another location and changed their names. Traditionally, 36 "royal races," or raj-kul, were known as Rajputs.
The term Rajputra was first used by Harshavardhan (606-648 AD) of Kannauj.
There is misconception that Rajputs are migrants to India from Central Asia who mingled with the aboriginal tribes and were given Kshatriya, or warrior status by the priests, however this view is not supported by the archaeological evidence that has come to light in the past century. ( Also see Death of the Aryan Invasion Theory)
During the rule of the British, Lieutenant Colonel James Tod visited Rajasthan and attempted to write a definitive list of the 36 Rajput tribes. However, everyone that he spoke to gave him varying lists of tribes. It can thus be concluded that a tribe that had furnished warriors or was politically dominant in a particular region can justly call itself a Rajput tribe.
Bhagwan Ram and Lakshmana are referred to as Rajaputra in Ramayana. Bhagwan Buddha was also referred to as Rajaputra in Buddhist texts. Dr. Rhys Davids in his "Buddhism, Its History and Literature: Page 27" says about Lord Buddha:
Abhimanyu's son Parikshit is called Rajaputra in Bhagvat Purana. Rajaputras have also been referred to in Kautilya's (350-283 B.C) Arthashashtra, Kalidasa's (1st century B.C) Malvikagnimitra, Asvaghosha's (80-150 A.D.) Saundarananda, Banbhatta's (7th century A.D.) Harshacharita and Kadambari and Kalhana's (12th century A.D.) Rajatarangini. Damodarpur copper-plate inscription of Kumaragupta III (533 A.D) records that the Governor of Bhukti of Pundravardhana, Rajaputra-Dev-Bhattaraka, was a son of the emperor, bearing the title Uparika Maharaja and 'rendering his homage to the king'. Rajputra are also mentioned in Sumandala Copper Plate inscription of Prithvigraha, Gupta era (570 A.D). There are Rajputra references in many Licchavi inscriptions (Recorded in D.R. Regimi's, Inscriptions of Ancient Nepal, Abhinav Publications, ISBN 0391025597). Rajputra Vajraratha, Babharuvarma, and Deshavarma are mentioned in the inscriptions of Sikubahi (Shankhamul) which describe the reigns of Licchavi kings Gangadeva (567-573 A.D) and Amshuvarma (605-621 A.D) respectively. The inscriptions of Sanga mentions the name of Rajputra Vikramasena, Gnoli inscription mentions Rajaputra Jayadeva, inscription of Deopatan mentions Rajputra Shurasena, and the inscriptions of Adeshwar mentions the Rajaputras Nandavarma, Jishnuvarma and Bhimavarma.
In 606 A.D. King Harshavardhana of Kannauj was crowned as Rajaputra Siladitya. Following excerpt from Page 146, of Advanced History of India written by R.C. Majumdar, H.C. Raychaudhuri, and Kaukinkar Datta, ISBN 0333 90298 X:
It is however, certain that Harsha found himself at the head of the kingdom of his brother as well as that of his brother-in-law. But he contended himself at first with the modest title of Rajaputra Siladitya. Apshad inscription of Adityasena (8th century A.D) mentions Madhavagupta who is identical with Madhavgupta, the Malawa Rajaputra of Bana's Harshacharita. Nadol Plates of 1161 A.D. mention Rajaputra Kirtipal, the progenitor of Songara (Svarnagiri) Chauhan dynasty of Jalore. Delhi Shivalik Pillar inscription, dating to A.D. 1163 of Chauhan King Virgharaj IV (Bisaldev) refers to his Mahamantri (Chief Minister) as Rajaputra Sallakshanpal.
The Rajputs did not originate as a tribe or a single community. They emerge from history as a collection of clans ruling different regions. The term Rajput as it is used today refers to the set of intermarrying royal clans. Two lists of 36 clans are found in Kumarpala Charita and the Prithviraj Raso compiled in Rajasthan region. Some of these clans are still quite well known (Parmara, Rever, Chalukya, Parihar, Chauhan, Rathore, Rawat, Thakore), some others are not as common (Gohil, Chapotkat, Kalchuri etc), while yet other names are hard to identify; apparently, with the loss of their domains and status, they dropped out of history. Any speculations as to the origins of the Rajputs has to be presaged with the caveat that in general, no single origin-theory can be held to be authoritative. The traditional occupations of the Rajput are war and agriculture. Many scholars have pointed out that these areas lend themselves uniquely to the ingress of groups that were not formerly affiliated with those professions. The gradual accommodation of the new entrants into the social and family circle of the traditional community is the essential quid pro quo of the sanskritization that the aspirant community essays. This phenomenon of gradual inclusion has indubitably obtained in the case of the Rajputs.