Maithil Brahmins ( Brāhamaṇas is the correct Sanskrit term) form part of ancient Vedic Brahmins. Maithil Brāhamaṇas are a part of Panch-gauda Pañchgauḍa , a group of highest ranking castes among Brahmins, who still strive to follow rites and rituals according to ancient Hindu canons. Maithil Brahmin is a community of highly cohesive, and traditional Brahmins. They are reputated for orthodoxy and interest in learning. Most of them live in and around Mithila, which is a portion of North Bihar and few districts of South-east Bihar up to Godda and Deoghar in Jharkhand of India plus adjoining Terai regions of Nepal. Mithila was the name of capital of the ancient kingdom of legendary King Janak. Most of them are Śāktas (worshippers of Śakti) and love Choora-dahi (Beaten rice - Curd), Sugar, Pickle, Mangoes and discussions and debate. Maithili is their mother tongue, though many use Angika (a southern variant of Maithili) as their mother tongue.They have four hierarchically ordered divisions: Śrotiya, Yogya or Joga, Panjibaddha (Pāinj in Maithili) and Jayawāra or Jaibar (which can be divided into Grihastha and Vamśa according to some scholars). They have no further endogamous divisions but observe a complicated rules for marriage, each of these four divisions may take a wife from the group below it.They are organized into named patrilineal groupings, and the genealogical links within and between these groupings has been an essential feature of Maithil Brahman social life for centuries. A class of genealogists known as panjikaras maintain records of the lineages and marriage links between them for the higher ranking lineages.
The Mithila Khanda of Visnu purana defines the traditional boundaries of Mithila as the Kosi River in the East, Gandaki or Gandaka in the west, Himalaya in the North and Gangā (Ganges) in the south, measuring 24 yojanas (1 yojana measured 12.52 Kilometres in 550AD according to Panchsiddantika ) east-west and 16 yojanas north-south. But now many districts south of Gangā are also included in Mithila by dint of being the region of Maithili language as well as the residence of Maithil Brāhamanas. Mithila is the traditional region associated with Maithil Brāhamanas, but a large number of Maithil Brāhamanas have been living in various parts of Madhya Pradesh (esp. Māndla region) and Chhattisagarh states for millennia. Few Maithil Brāhamanas also reside in uttarakhand garhwal region e.g. Uniyal Brāhamanas. In addition, Maithil Brahmans have now migrated all over the world.Mithila region comprises following districts in India :Darbhanga, Saharsa, Bhagalpur, Purnea, Madhubani, Samastipur, Begusarai, Supaul, Madhepura, Sitamarhi, Sheohar, Muzzafarpur, Khagaria, Katihar, Araria, Banka, Godda, Deoghar, Jamui, Munger and following districts in Nepal: Morang,Sunsari, Saptari,Siraha, Dhanusa, Dhanusa,Mahottari, Sarlahi,Rauthat,Bara, Parsa,etc.
Uttarakānda of Vālmiki Rāmāyana (Ramayana) gives a detailed story of the origin of Maithil Brāhamanas. The King Nimi started a great yajna in which he invited rishi Vasiṣṭha for performing this yajna. Vasiṣṭha accepted but was busy in another yajna for a long time and therefore could not come in time. In the meantime, King Nimi asked the rishi (sage) Gotama to perform the yajna. Many other rishis were also invited. When Vasiṣṭha came and saw that the yajna was over, he cursed Nimi to live without body. Nimi retorted with a similar curse. By the blessings of his father Brahma, Vasiṣṭha was reborn in a kumbha (pitcher). Bhrigu and other sages asked the bodyless king Nimi whether he wanted to get a body, but Nimi refused and said he wanted to live in the 'pupils'(eyelids, Nimi) of people. Then Nimi's body was churned and a man was created, who came to be called Videha because he was born of a father who had no body (deha), and was also called Maithil because he was produced by churning (manthana). All the present gotras of Maithils are said to start from the sages who participated in the great yajna of Nimi. Yajnayalkya lived in Mithila (according to Brihadaranyaka Upanishada) and proponents of India's six philosophies also lived herew, including Gotama (Nyaya), Kapil(Samkhya),etc. Buddhism was widespread here. Later Udyotkata, Kumarila Bhatta, Mandana Mishra, Prabhakara, Udayanacharya, Gangesh, Pakshadhara Mishra, etc reestablished the Vedic religion by defeating Buddhists in debates. .According to D.D. Kosāmbi, Śatpath Brāhmana tells that Māthava Videgha, led by his priest Gotama Rahugana, was the first king who originally lived in the land of Sarasvati crossed Sadānirā (supposed to be Gandaka) and founded a kingdom, where the people named videhas lived at the time of composition of Śatpath Brāhmana. Gotama Rahugana was a vedic rishi who composed many hymns of the first mandala of Rgveda. Most notable Rgvedic hymns of Gotama Rahugana are those which praise Sva-rājya, which was indisputably the State of Videgha which later became Videha due to phonetic change. Māthava Videgha, therefore, must belong to the Rgvedic period and must have preceded the period of Śatpath Brāhmana by a considerable gap. Rgveda also mentions hymns by Kāśirāja Pratardana in tenth mandala. Hence, Mithilā and Kāśhi formed part of the region in which Rgvedic peoples lived. Descendandants of Gotama Rahugana were called Gautama. One such sage lived near Ahilya-sthāna during the age of Rāmāyana.