The spread of Babylonian rabbinic influence between the Sasanian and early Islamic period remains poorly understood. Though a minor movement of seemingly little influence at the outset of the Sasanian period, by the 10th century the Babylonian rabbis commanded respect from Jewish communities from Andalusia to Khorasan. This paper reexamines this transition by highlighting the ways in which broader historical trends of the late Sasanian and early Islamic Empire - including economy, postal services, urbanization, migration patterns, trade routes, and more - facilitated the growth and spread of Babylonian rabbinic influence. The elusive nature of this period is a product of our limited source material. As a result, scholars have either retrojected the influence of Babylonian rabbis in the 10th century on the Sasanian period itself, or despaired of providing any account due to the lack of evidence. This paper argues that there remains untapped evidence for Jewish life in this period, and that a structural methodology that situates Babylonian Jewish life within the broader historical trends of the time reveals new light on this crucial transition period. An examination of all of the available evidence for Babylonian Jews between the 6th-9th century - including Babylonian Jewish incantation bowls, Byzantine and Arabic historiographical sources, and the earliest responsa produced by Babylonian rabbis in the mid to late 8th century - reveals the rise in local recognition of Babylonian rabbis as a result of the major social and economic shifts of the Sasanian sixth and seventh century, to the expansion of their influence in the 8th century and onwards. Key transitions following the conquests facilitated the further spread of rabbinic influence. The well-known trend towards urbanization - mentioned in an early responsum - relocated rabbinic supporters to major cities, while compelling rabbis to spread their network to maintain - or increase - their financial resources. The related trend of migration, and the development of trade networks across the Arab-Muslim world, created satellite Babylonian communities in both the east and west. The major bailiwick of Babylonian rabbis, however, according to a number of sources, appears to have been Jewish communities in Iran, a fact occasionally acknowledged but rarely integrated as central components in the spread of rabbinic influence. By triangulating our available evidence for Babylonian Jewish life and our knowledge of broader structural developments of the time, this paper offers a new picture of this momentous period of transition.