The Indo-Aryan or Indic languages are a subgroup of the Indo-Iranian languages, in turn a subgroup of the Indo-European languages. They are primarily spoken in India and neighboring areas. "Indo-Aryans" may broadly refer to all native speakers of Indo-Aryan languages or more narrowly to the Indo-Europeans who according to the Indo-Aryan migration theory invaded / colonized India. The term "Aryan languages" is sometimes used as a synonym for Germanic languages.
Indo-Aryan migrations & Controversy
After World War II, the term Aryan and the idea of Aryan migrations became controversial due to its usage in Nazi Germany. However, genetic evidence has vindicated the Aryan Invasion theory  and found that the peoples who invaded India came from the Andronovo Culture, who came from the European Corded Ware culture and were genetically similar to modern Northern Europeans. This DNA is highest in India today among the prestigious Brahmin caste, implying that these Aryans formed a somewhat endogamous elite and imposed their religious system on the locals.
Early Indo-Aryan Society
The early elements of Indo-Aryan Society can be seen in the Rig Veda, which is the oldest Veda dated to ~1500 BC. It depicts a society similar in many ways to other Indo-European societies (see: Indo-European). In the Rig Veda, several passages have been argued to refer to the Dasyu, the enemies of the Rigvedic Indo-Aryans, as black-skinned. Others argue that "Black Skin" (kṛṣṇa tvác) is metaphorical or mistranslated, however tvác is etymologically related to other Indo-European words meaning "skin" or "hide", and is used to refer to skin/hide in Vedic texts as well.
Varna, a term which describes the divisions in Indian society attributed to Castes (Brahmin, Kshatriya, Vaishya, Shudra), also originally meant outward appearance, and later directly referred to color or pigmentation. In some texts it also refers to tribe, race or kindred.  In the Mahabharata section 12,181.005, the four Varnas (with Varna still meaning color or pigmentation at this time) were assigned as follows: Brahmins were of White complexion, Kshatriyas of red, Vaishyas of yellow, and Shudras as black. If one follows Georges Dumezil's Trifunctionalism hypothesis, the higher 3 Varnas represent the 3 parts of Indo-European society. This has caused some to speculate that the Shudra are a product of the pre-Aryan inhabitants of India rather than an original Caste.
Common arguments made against this is that the usage of color or skin tone in the Vedas and later texts may be completely symbolic. However, the preservation of greater degrees of Steppe DNA in Brahmins over the course of thousands of years suggests that there must have been some degree of discrimination between the Aryans and the pre-Aryan peoples of India. Several Vedic and Classical Indian texts describe the Brahmins as light-complexioned with bright hair colors. Such traits are uncommon in India and Pakistan today, only found particularly often among the isolated Nuristanis and Kalash. Both of these peoples retained a religion very similar to Vedic polytheism until either very recently in the case of Nuristanis, and up to present times in the case of the Kalash. Genetic studies on the Kalash suggest they are up to 50% Steppe Ancestry but there are no known Genetic samples on the Nuristanis.
- Encyclopedia Britannica: Indo-Aryan languages
- Encyclopedia Britannica 1911 Edition: Indo-Aryan Languages