The image here is from Univ. of Chicago professor William McNeill’s 828-page book on Western Civilization (1991) in which he noted on the copyright page, “I seek to understand...” 

Prof. McNeill wrote that Iranians were a “model first for Byzantium and through Byzantium for remote western Europe, where aristocratic armored cavalry became the basis of local self-defense a full thousand years after the development of a similar system in Iran.”

…we can see from his drawing here that Iranian Parthian Empire (247 BCE-224 CE) played a major role in this military transmission…

Prof. McNeill pointed out that the Roman conversion to Iranian-style large-scale cavalry began in 4^th century CE after Constantine the Great’s time…further, “Persian influence on the Byzantine state was not confined to the sphere of military technology. From the time of Diocletian (284-305), the rulers of the Roman empire deliberately copied aspects of Persian courtly ritual and sovereign splendor.”

…Mainstream Fake Education does not convey this relationship between Asiatic Iranians (recall, Iranians are both European and Asiatic) and Europeans in the so-called college history textbooks that I surveyed… but mostly tend to falsely promote, appease, or justify today’s anti-Iranian Islamo-Marxists in Tehran as representatives of Iran’s historical identity, presence, and achievements…

…glorification and legitimization of Islamism (Islamic theocracy) is mutually incompatible to Iranian-based governance…

[pic W. H. McNeill: for educational purposes only]