The book compiles and analyzes the body of words and Person Names, attested in the Ancient Near East during the second millennium BC, which are or may be of Indo-Iranian origin. Many have been surveyed by Mayrhofer (1966, 1974) but a number have often been overlooked or mischaracterized as foreign or Kassite.
Horses, horse-riding and weaponry have obviously played a major role in the expansion of Indo-Iranian.
Conspicuous are the gods (Mitra, Aruna, Indar, Nasattiya) mentioned in Hurro-Hittite treaties.
The bulk of Mittani-Aryan has phonetic features similar to those of Indo-Aryan. But some words suggest that another Indo-Iranian language is attested in the corpus and does not have the same phonetic features.