Upamanyu was one such Rsi of Kamboja lineage who finds frequent mention in ancient Indian Vedic as well as epic texts.
and also in Anushasana Parava of epic Mahabharata (XIII.14-17) . Sage Upamanyu is said to be the father of sage Kamboja Aupamanyava referred to in the Vamsa Brahmana (1.18) of the Sama Veda .
The Story of Rsi Upmanyu
Upamanyu was one among the favourite disciple of sage Ayodhdhaumya, along with Aruni of Panchala and the one named 'Veda' (Mbh 1.3). Upamanyu was assigned the task of looking after the cows. One day when he returned after his days work, the Guru called him and said, "Son, you look very healthy and radiant. What do you eat while you are working?" Upamanyu replied with all humility, "Sire, I eat whatever I get in alms." The saint who wanted to test Upmanyu said that from now on he would not eat anything that he received as alms without first asking him. Upmanyu agreed and from then on offered all that he received to his guru. The Guru would take everything and give Upamanyu nothing.
A few days later, the Guru again asked Upmanyu, "I take away all that you beg for, so what do you eat?" Upamanyu replied that whatever he received by begging the first time, he offered it to his Guru and then went out and begged again a second time. The guru said, "Son, this conduct is inappropriate for a resident of the hermitage. By begging twice you hinder the earnings of other pupils as you cut into their share of alms. Besides this also proves your greed."
Upamanyu listened to the guru and agreed not to do so again. A few days later, the guru again asked Upamanyu how he still looked so robust when he had stooped him from eating anything. To which Upamanyu replied that he drank a little of the cow's milk while he took them out to graze. The guru forbade him to do that without his permission. A few days later, on seeing Upmanyu still looking healthy, the guru again called him and asked how he was surviving. This time Upamanyu said that he drank the foam that the calves drooled while feeding on their mother's milk. The guru again forbade Upmanyu to do so and said that this would affect the health of the calves as they would drop more and more foam for Upamanyu to feed out of the kindness of their heart.
Upamanyu agreed to this too and went back to graze the cows as was his duty. Now that all avenues of getting food were closed, Upamanyu felt really hungry. When he could not tolerate the intensity of hunger he went and ate the leaves of a plant called `Aak', the leaves of which produce a bitter, sour, acidic and poisonous juice. Due to the effect of this juice Upamanyu was instantly blinded. He kept wandering in the woods and fell into a dry well.
After sunset, when Upamanyu did not return to the hermitage, the saint started worrying about him. He said to his other pupils, "I have closed all avenues for Upamanyu to get food. He is probably angry at this and hence has not returned, so let us all go and look for him." So they went to the woods to look for Upamanyu. They called out for him and heard a feeble voice from the well. They hurries to the well and when they peeped inside they saw Upamanyu. They asked Upamanyu how he fell inside the well. Upmanyu said, "I was so hungry that I ate the leaves of the Aak plant. I then became blind and while I was trying to find my way home I fell into the the well." After hearing his story they pulled him out of the well and his Guru told him to pray to the physicians of the Gods, Ashwini Kumar, so that his eyes would be healed. Upamanyu did as he was told and and Ashwini Kumars (twins who are the Physicians of Gods) appeared before him. They said, "Upamanyu, eat this sweet that we have brought you and you shall be healed." Upmanyu declined and said that he cannot eat anything without the permission of his guru. The gods then told him that they had offered his guru some sweet and he ate it without asking the permission of his own Guru. So if it is okay for your Guru to eat without first asking permission from his own guru then it is okay for you too.
But Upamanyu again declined and this devotion and obedience of Upmanyu towards his guru pleased the gods. They blessed him and Upamnyu's eyes were healed and all his teeth turned into gold. Upmanyu then went to his guru and was blessed by him. His guru was so pleased with him that he blessed him with instant memory and told him that he will know the Vedas and Dharamshashtras (other religious texts) automatically without any effort.
Upamanyu is the composer of Rig Vedic Hymn 1.102.9 .
Upamanyu also is one of the gotras of Hindu brahmins. The people with Upamanyu gotra live in far western part of Nepal and eastern Parts of Jammu & Kashmir. They are basically present just below the Mount Kailash as they pray to Lord Shiva only.
Prof B. N. Datta comments: "...In the list of Brahmana gotras mentioned in the Matsya-Purana , the name of (Kamboja) Aupamanyava is to be found. It is said to be an offshoot of the Vrigu (Parasara) gotras. This means that a Rishi hailing from the Kamboja tribe was also founder of a Brahmanical class.......Weber says that the appearance of the name of Kamboja (an Indian sounding name in Vedic text) as a Sama theologian is analogous of the discovery of the name of Gautama in Zoroastrian Mithra-Yesht . Upamanyu was of Kamboja descent, and Ustaxri was probably of Bactrian origin. Further, the name of prominent Rishi like Atharva sounds like Atharavan or Atharvan, the Persian fire-cult priest. The names of Atharva and Angirasa are connected with the introduction of fire-cult amongst the Vedic people. In this case, we find another infiltration of the foreign element (Kambojas etc) in the ethnic composition of the Vedic Aryas" .
DOGRAS / DUGGAR HILLS: People staying just below or the South (Eastern & Weastern) parts of Mount Kailash (Nepal & India) are the decendants of Upmanyu / Upamanyu Gotra. In India the region of Jammu (Duggar Hills) are occupied by the decendants of Upamanyu (Kambojhas). The Kambhojas (after the Mahabharata) moved out from todays Afganistan and walked east near the Kailash Parvat. A few stopped mid way in Jammu, due to the similar climate of the Hindu Kush Mountains. Kambhojas being fierece warriors (refer Mahabharata) were excellent in Down Hill attack and Up hill attack. The similar tribe of Kambojhas with time, started writing their Surname as Duggars, Dogras, Duggal, Sharma etc. This was one of the reasons for the Prince of Wales to choose and create a regiment for his protection during his visit to India called the DOGRA REGIMENT as they had the qualities of the Gorkhas and the Sherpas collectively.
The Kambhojas (Upamanyu Gotra) can be easilty identified as they are fair and have colourful eyes (Yellow, light blue, light brown) with a bit broader Forehead & nose. Dogras have hot blood and are very fond of food & drinks. Although Drinks are a absolute NO for the Brahmin clan of Kambhoja. Only the Rajput clan of Kambhoja / Upamanyu can consume Alcohol.
Praying to Lord Shiva every monday is a must for all Kambhojas / Upamanyu Gotra (All clans). The Brahmins under the Upamanyu Gotras can change their destiny just by not consuming any non - Veg, alchohol & tobacco. A visit to Lord Shiva's Temple every Monday is a must for every Upamanyu Gotra. This helps in progrssing in the individuals life. Kambhojas / Upamanayu gotra prays to Lord Shiva & Durga Maa is their Kula Devi.