In Hindu culture, the term gotra (Sanskrit: गोत्र) is considered to be equivalent to lineage. It broadly refers to people who are descendants in an unbroken male line from a common male ancestor or patriline. Generally, the gotra forms an exogamous unit, with marriage within the same gotra being regarded as incest and prohibited by custom. The name of the gotra can be used as a surname, but it is different from a surname and is strictly maintained because of its importance in marriages among Hindus, especially among castes. Pāṇini defines gotra as apatyam pautraprabhrti gotram (IV. 1. 162), which means "the word gotra denotes the descendance (or descendants), apatya, of a couple consisting of a pautra, a son and a bharti, a mother, i.e. a daughter-in-law." (Based on Monier Williams Dictionary definitions.) When a person says "I am Vipparla-gotra", he means that he traces his descent to the ancient sage Vipparla by an unbroken male descent. According to the Brihadaranyaka Upanishad 2.2.4, Kashyapa, Atri, Vasistha, Vishvamitra, Gautama Maharishi, Jamadagni and Bharadvaja are seven sages (also known as saptarishi) and Jambu Maharishi is another sage (also known as Renuka, who belongs to Kashyapa). The progeny of these eight sages are declared to be gotras. This enumeration of seven primary & one secondary gotra seems to have been known to Pāṇini. The offspring (apatya) of these seven are gotras and others than these are called gotrāvayava. One who follows the system defined by three sages defines himself as Tri-a-Vishay. Similarly, for five sages, it is Pancha-Vishay, and for seven sages, it is Santa-Vishay. There exists another theory about gotra: sons and disciples of a sage would have the same gotra; it is believed that they possess similar thoughts and philosophies. People of the same gotra can be found across different castes. Each gotra comprises pravaras. Origins As a Rigvedic terms, gotra simply means "forward moving descendants". (गौः) गमन करनेवाली means forward moving and (त्र:) stands for Offspring. The specific meaning "family, lineage kin" (as it were "herd within an enclosure") is relatively more recent, first recorded around the mid-1st millennium BCE (e.g., Chandogya Upanishad). These "lineages" as they developed among the Brahmins of that time meant patrilineal descent. The Brahmanic system was later adopted by other communities, such as the Kshatriyas and Vaishyas All members of a particular gotra are believed to possess certain common characteristics by way of nature or