In a western oriented website it would be tempting to use western categories of race, etc., but that would perpetuate the colonial race-oriented mindset of denigrating eastern traditions. Firstly, the word Aryan itself is not a race, but a title denoting nobility and was rarely used in Indian scripture and misappropriated by Hitler/Muller etc. Secondly, the Aryan migration/invasion theory has been completely disproved so it is also inappropriate to say that Iyengars were of "Indo-Aryan" stock. In fact, the Iyengars as a group are best referred to as a "Jati/Kulam" within the traditional Hindu system, all completely native to their Indic homeland.
Iyengars are well known as Vaishnavite and or the followers of Lord Vishnu. Iyengars fall under Brahmin Community of Hinduism, as are their Smartha counterparts, the Iyers. Like all brahmin communities,the Iyengars are also classified based on their gotra, or patrilineal descent from great Rishis of yore. The native tongue of the Iyengar brahmins is Sanskrit & Tamil. But nowadays there are Iyengars who speak other languages, mainly Telugu, Kannada, Malayalam. Vaishnavites have been living in the Tamil Nadu state of the Republic of India even prior to the time of Ramanuja. However, Iyengars as a community trace their origin from the times of Ramanuja.
In many cases, both Iyers and Iyengars are mistakenly referred to as "Ayyar" as they are indistinguishable from Iyers in their adherence of the Vedic tradition. However, Devout Iyengars sport a namam ((thiruman+srichoornam)) as a mark of "bhakthi" as opposed to Iyers who apply vibhuti, generally on their forehead.