[2] In contrast to widespread notions associating the Silk Road with China, he sees the premodern trans-Asian trade networks as having been driven by the activities of traders who were mostly of Iranian background, principally Sogdians but also Parthians and Persians.

"[4] In addition to religions commonly associated with Iran such as Zoroastrianism, Manichaeism, Islam and the Baháʼí Faith, Foltz's work highlights the influence of Iranian ideas on Judaism, Buddhism and Christianity.

His book A History of the Tajiks: Iranians of the East is the first monograph on the subject to be written in any Western language,[5] as is his The Ossetes: Modern-Day Scythians of the Caucasus.

[7] Commenting on the broad sweep of Foltz's attention to Iranian civilization, a reviewer writes in The Muslim World that "No scholar, save perhaps such giants as Ehsan Yarshater and Richard Frye, can claim a depth of knowledge of traditions as diverse and covering such a wide historical span".

[11] Foltz has been deeply critical of global capitalism, seconding scholars such as David Loy and Harvey Cox who argue that the dominant faith system in the world today should properly be referred to as the "Religion of the Market".