An Atreya (आत्रेय) is a descendant of Atri, one of the great Hindu sages (rishis) whose accomplishments are detailed in the Puranas.
The descendants of Atri Rishi use Atreya as their surname just like many other Gotras, or clan names used by the Brahmin community of Hindus in India and Nepal. In Northern India, most Atreya Brahmins also prefer to use the Tyagi surname. Many of the Kshatriyas of South India also belong to this Gotra.
Original Atreya gotri bramhin have migrated to the East Indian state of Orissa which was in the ancient time known as Kalinga, Utkala/Utkal, South Kosal, Kongada, Odra Desha, etc. All Oriya-Utkala Brahmins with the surname Rath belong to the Atreya gotra in the line of rathātreya (रथात्रेय). People with the surname Paudel also belong to this Gotra. a son of Atri and compiler of the Ṛk Veda, 5th Maṇḍala. Nepali Brahmin castes like Dulal,Pokhrel,Sharma etc. are known as Atreya Gotra.
Influences
According to the Charaka tradition, there existed six schools of medicine, founded by the disciples of the sage Punarvasu Ātreya. Each of his disciples, Agnivesha, Bhela, Jatūkarna, Parāshara, Hārīta, and Kshārapāni, composed a Samhitā. Of all the six, the one composed by Agnivesa was most revered. But, neither of them has survived.
Charaka later on, taking cues from Agnivesa Samhita, produced the now renowned work Charaka Samhita around 300 B.C. which survived and has been handed down to us in the form of Bower Manuscript dated around the 4th century. Charaka Samhita is the foundational text of Ayurveda.