Instead, he transferred to the University of California, Los Angeles, to study with Gustave E. Von Grunebaum and Nikki Keddi. Garthwaite's primary interest is Iran, but he covers all of the Islamic Middle East in his teaching. His courses span a period from the seventh century to the present. They include "The Eye of the Beholder: Introduction to the Islamic World," "The Arab World in the Twentieth Century," "Topics in Middle East History: History of the Middle East," "Social History of the Contemporary Middle East," and "The Arab-Israeli Conflict." "My purpose in teaching," notes Garthwaite, "is to imbue my students with an understanding of, and an appreciation for, one of the world's great, but little-known, cultures and with critical thinking."
Garthwaite notes that his research "deals with Iranian social history and culture, particularly the Bakhtiyari, one of Iran's great tribal confederations." Garthwaite is the author of Khans and Shahs: A Documentary Analysis of the Bakhtiyari in Iran, a volume that is mentioned on the Bakhktiari.com Web site, which uses an alternate spelling of the name. An excerpt from the book is provided, which reads: "The Bakhtiyari have constituted a continuing, relatively changeless sociopolitical unit isolated for centuries; its leaders' roles date from antiquity; the link between the khan and his tribesmen, between power and the pastoral economy with its ties to the wider society, is self-evident."
Garthwaite is also the author of The Persians, a narrative of the history of Iran from the time of Cyrus the Great in 560 BC until the present. Events covered include the rise of the Persian empire, its competition with Rome, Arab conquest, reestablishment of the Persian state in the sixteenth century, the Islamic Revolution of 1979, and the evolution of the contemporary Islamic Republic. Chapter titles include "Persia: Place and Idea," "The Achaemenians (c.550-331 BC)," "Alexander (330-323 BC), the Selucids (312-129 BC), and the Parthians (247 BC-AD 224)," "The Sasanians (c. 224-651)," "‘Non-Iran’: Arabs, Turks, and Mongols in Iran," "The Safavids (1501-1722)," "The Qajars (1796-1926)," and "Iran: 1921-2003: Pahlavi and Islamic Republican Iran."
The Persians was reviewed by two Historian contributors. Richard W. Bulliet commented that the volume "comes at a time when interest in Iran is reviving, both because of political events and because Iranians raised in the diaspora are seeking to understand their origins." Bulliet noted that the amount of space given to the subjects varies. Ninety pages are devoted to the last two hundred years, forty-four cover the two hundred years of Achaemenid rule, and just twenty pages are allotted to the five centuries that separated the Achaemenids from the Sasanians. "In most instances, the disparities arise because of uneven source materials or an understandable desire to emphasize recent events," added Bulliet.
Historian reviewer Charles Melville noted that the subjects of the book are called Persians only for the pre-Islamic period, after which they are called Iranians. "What follows," wrote Melville, "is a largely political history of Iran, with a very strong focus on the question of dynastic legitimacy and the idea of universal rulership, which seeks to embrace the multiracial and pluralistic constituencies of society and to act as the cement that holds it all together."
Garthwaite provides tables, maps, and a reading list in this study of Persian/Iranian identity, political culture, and religion. Melville described The Persians as "a useful introduction" to this long period of Iranian history.