Ṣāṇdilya was the name of at least two prominent rishi

Rishi

Rishi denotes the composers of Vedic hymns. However, according to post-Vedic tradition, the rishi is a "seer" to whom the Vedas were "originally revealed" through states of higher consciousness. The rishis were prominent when Vedic Hinduism took shape, as far back as some three thousand years...

s. One of the rishis was the progenitor of the Sandilya

Sandilya

Śāṇḍilya is one of the Brahmin gotras, named after the eponymous rishi Śāṇḍilya, specifying that individuals of the gotra have Śāṇḍilya for one of their patrilineal ancestors....

 gotra

Gotra

In the Hindu society, the term Gotra broadly refers to people who are descendants in an unbroken male line from a common male ancestor. Panini defines gotra for grammatical purposes as apatyam pautraprabhrti gotram , which means "the word gotra denotes the progeny beginning with the son's son"...

.

The name was derived from the Sanskrit

Sanskrit

Sanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism, Jainism and Buddhism.Buddhism: besides Pali, see Buddhist Hybrid Sanskrit Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand...

 words ṣan, full and dilam,the moon, with the derivative ya added, meaning the one of the full moon, thereby implying a priest or a descendant of the Moon God

Chandra

In Hinduism, Chandra is a lunar deity and a Graha. Chandra is also identified with the Vedic Lunar deity Soma . The Soma name refers particularly to the juice of sap in the plants and thus makes the Moon the lord of plants and vegetation. He is described as young, beautiful, fair; two-armed and...

.

Progenitor of Sandilya Gotra

One rishi was a son of the sage Asita

Asita

Asita was a hermit ascetic of ancient India in the 6th century BCE. He is best known for having predicted that Prince Siddhartha of Kapilavastu would either become a great king or become a supreme religious leader ....

 and grandson of the rishi Kashyapa, and the founder of the Ṣāṇdilya gotra. Brihadaranyaka Upanishad

Brihadaranyaka Upanishad

The Upanishad is one of the older, "primary" Upanishads. It is contained within the Shatapatha Brahmana, and its status as an independent Upanishad may be considered a secondary extraction of a portion of the Brahmana text. This makes it one of the oldest texts of the Upanishad corpus...

 states that he was a disciple of Vaatsya rishi
.
His other Acharya

Acharya

In Indian religions and society, an acharya is a guide or instructor in religious matters; founder, or leader of a sect; or a highly learned man or a title affixed to the names of learned men...

s include Kaushika, Gautama Maharishi

Gautama Maharishi

Gautama Maharishi is one of the Saptarishis Gautama Maharishi is one of the Saptarishis Gautama Maharishi is one of the Saptarishis (Seven Great Sages Rishi of the current Manvantara (seventh). He was one of the Maharishis of Vedic times, known to have been the discoverer of Mantras --...

, Kaishorya Kaapya, Vatsya Vaijavap, and Kushri. His disciples include Kaudinya, Agnivesa

Agnivesa

Agnivesha was an ancient Indian rishi , and myths of his birth associate his parentage to Agni. He was one of the earliest writers on ayurveda, the ancient Indian science of health and medicine. He was a pupil of Punarvasu Atreya.-References:...

, Vatsya Vamakakshayan, Vaishthapureya, and Bharadwaj
.
He was also the composer of the Ṣāṇdilya Upanishad

Upanishad

The Upanishads are philosophical texts considered to be an early source of Hindu religion. More than 200 are known, of which the first dozen or so, the oldest and most important, are variously referred to as the principal, main or old Upanishads...

. According to the Bhagavata Purana

Bhagavata purana

The Bhāgavata Purāṇa is one of the "Maha" Puranic texts of Hindu literature, with its primary focus on bhakti to the incarnations of Vishnu, particularly Krishna...

, he was instrumental in settling certain metaphysical doubts of King Parikshit of Hastinapura

Hastinapura

Hastinapur is a town and a nagar panchayat in Meerut district in the Indian state of Uttar Pradesh.-History:Hastinapur was the capital of the kingdom of the Kauravas, belonging to the Kuru dynasty of kings. The throne of this city was the prize over which the Kurukshetra War of the epic...

 and King Vajra

King Vajra (Vajranabh)

Vajra also known as Vajranabh , was one of the last surviving Yadu, who succeeded King Aniruddha to the throne, according to the Mahabharata and the Puranas. He was the great grandson of Krishna, the grandson of Pradyumna and Son of Aniruddha.-Meanings:1) Vajra also means thunderbolt or daimond...

 of Dwaraka.

Rishi from Shāradāvanam

The other, by some accounts, a son of the sage Vasistha

Vasistha

Vashist in the seventh, i.e the present Manvantara, and the Rajpurohit / Rajguru of the Suryavansha or Solar Dynasty. He was the mānasaputra of Brahma. He had in his possession the divine cow Kamadhenu, and Nandini her child, who could grant anything to their owners...

, had his hermitage in the Shāradāvanam, or forest of Sharada

Saraswati

In Hinduism Saraswati , is the goddess of knowledge, music, arts, science and technology. She is the consort of Brahma, also revered as His Shakti....

, of a village in the Bolair Valley of Kashmir. The village has been identified with the modern town of Sharda

Sharda Temple

Sharda is a small town situated in Azad Kashmir Pakistan. It is famous for its ruined temple structures. Sharda is situated in Neelum District of Azad Kashmir, 136 kilometers north of Muzaffarabad and it is one of its two tehsils....

, on the banks of the River Kishanganga

Neelum River

The Neelum River , or Kishanganga , is a river in the Kashmir region of India and Pakistan. The Neelam River enters Pakistan from India in the Gurais sector of the Line of Control, and then runs west till it meets the Jhelum River north of Muzzafarabad.- Neelum Valley :The Neelum Valley is a...

, in Pakistan-occupied Kashmir. The goddess Sharada is said to have manifested herself to him, here, after severe penance by him, to confer upon him his yagnopaveetham

Yagnopaveetham

The Yagnopaveetham is the triple stranded sacrificial strand of thread that is worn by those initiated into the Gayatri recital. The three strands represent the three sandhya rites that are to be performed when the sun rises and sets and when the sun is at the zenith. The rites are in adoration of...

, an event that was commemorated in the temple of Sharada Peeth

Sharada Peeth

Sharada Peeth , located near Sharda, was the famous temple of the goddess Sarasvatī in Northern Kashmir on the banks of what is known as the Neelum River in Pakistan . Its ruins are now in the Neelum District of Pakistan Administered Kashmir near the Line of Control and Gurez, India...

in the town.