What are some of the apparent themes of Indo-European mythology that influenced Roman mythology?
Scholars have proposed the existence of several cultural themes that characterize Indo-European mythologies from India to Iran to Europe—including Rome.
The first of these is tripartization, the dividing of society into three classes: religious, military, and farming and herding. In India these classes are represented by Brahmins (religious caste), Kshatriyas (warrior caste), and Vaishyas (farmer caste). In Rome the same classes were the flamines, the miletes, and the quirites. In Roman mythology sovereign gods were related to priests and kings, warrior gods to warriors, and fertility gods to farmers. An outgrowth of tripartization is the ubiquitous presence of the Indo-European triad of gods representing sovereignty, power, and community: Brahma, Shiva, and Vishnu in Hindu India, and Jupiter (Iuppiter), Mars, and Quirinus in ancient Rome, for example.
Twins are another important aspect of Indo-European mythologies. The Ashvin twins in India had counterparts in Castor and Polydeuces (Pollux) in Greece and in Remus and Romulus in Rome.
The theme of the warrior hero is basic to Indo-European mythology. Arjuna in India, for example, has a Roman relative in Aeneas.