The Britannica website has this information about a lost sect of Asia Minor.

Saura sect, Hindu sect, widely dispersed throughout India in the Gupta and medieval periods, whose members worshipped Surya, the Sun, as the supreme deity. The Vedas (the sacred scriptures of Hinduism) contain a number of hymns to Surya as well as to a number of other solar deities, and the Mahabharata mentions a sect of Sun worshippers. The Sauras believed that the worshipper could attain spiritual emancipation (moksha; literally, “release”) by adoring the Sun (just-risen, on the meridian, and setting), by bearing its marks on the body (a circular red tilak on the forehead), and by chanting Surya’s prayer.

The influence of the ancient Iranian worship of Mithra is evident as early as the 1st century ce. Thereafter, North Indian temple images of Surya show him in typical northern dress, such as boots, and the girdle around the waist known as the avyanga (Avestan avyonhana). The Magas (Iranian priests, or Magi) were the special priests of the sun gods and were assimilated into the Hindu class structure as Brahmans. The temple constructed at Multan on the banks of the Chandra Bhaga River (modern Chenab River, now in Pakistan) was an important centre of the movement in the 7th century ce.

Though the Saura sect is no longer prominent in India, many Hindus chant the Gayatri mantra, a prayer to the Sun, at every dawn. Surya also figures as one of the five deities (together with Vishnu, Shiva, Shakti, and Ganesha) worshipped by the Smarta sect.

Heliolatry is in decline in modern India but that's not how it was in the past. The treatise between the Aryan-Mittani and the Semite-Hittite kings around 1500 BC mentions the four Vedic gods Indra, Mitra-Varuna and the Asvins.

"The proto Indo-Iranian religion started off as sun worship" - Max Mueller

The western world is completely misinformed about the religious beliefs of the Aryan people. Visnu, Krishna, Shiva, Durga, Kali, Laskhmi, The Elephant God - Ganesha, The Snake God - Murugan, The monkey God - Hanuman are not mentioned in the Vedas and Visnu was a lesser or a minor deity in the Vedas. For more information read the article "Why Vedism" by A Druid Fellowship (ADF), Adhitin Ratrija with N. Agnayi.

Helios-Mithras, the God of Julian the Emperor, Sol Invictus, the invincible unconquerable Sun was the same Sun god that the Aryans believed in and worshiped him as the soul of the cosmos. Sun God, Savitr is the master of the Vedas and it was he who revealed the Vedas to the world through the Vedic seers.