Map Introduction

I. Establishment and Early Development of the Jiannan Circuit (Early Zhenguan Era – Kaiyuan Era)

The Jiannan Circuit was one of the ten circuits established in the first year of the Zhenguan era (627 AD) under Emperor Taizong of Tang. Its name derived from its location south of the Jianmen Pass, and its administrative seat was at Yi Province (modern Chengdu). Its territory encompassed most of modern Sichuan, eastern Yunnan, northern Guizhou, and the Wen County area of Gansu, serving as the Tang dynasty's core region for controlling the southwestern tribes. Initially functioning primarily as a surveillance district, a Military Governor of Jiannan was added in the 21st year of the Kaiyuan era (733 AD), strengthening military control and transforming it into a forward base for resisting the Tibetan Empire and Nanzhao.

II. Division and Functional Transformation after the An Lushan Rebellion (Qianyuan Era – Late Tang)

Following the An Lushan Rebellion, the Jiannan Circuit was divided into Eastern and Western Chuan in the first year of the Qianyuan era (758 AD): Western Chuan administered from Chengdu, and Eastern Chuan from Zi Province (modern Santai County). This adjustment stemmed from the Tang court's strategic reassessment of the southwest – Western Chuan focused on military defense, while Eastern Chuan handled logistics and transport. Chengdu, renowned for its "rich land and populous people," became a refuge center during the turmoil, hosting both Emperor Xuanzong and Emperor Xizong. The Jiannan Circuit maintained connections with the Guanzhong region via post roads like the Jinniu Road and Chencang Road, becoming a vital "granary" and "strategic rear area" for the imperial court.

III. Economic Status and Ethnic Governance

The Jiannan Circuit was economically prosperous, earning the saying "Yang [Zhou] is first, Yi [Chengdu] is second." While its registered households, which numbered 910,000 in the first year of Tianbao, declined sharply after the An Lushan Rebellion, it remained a crucial source of tax revenue. The area was inhabited by many non-Han ethnic groups like the Lao and Qiang. The Tang dynasty established loosely administered Jimi prefectures for indirect rule, maintaining stability in areas like Ya Province and Qiong Province through strategies of "using barbarians to control barbarians." As a cultural hub, Chengdu attracted numerous aristocratic families fleeing south from the Central Plains. The cultural symbolism of the region is later reflected in Lu You's Poetry Manuscript of Jiannan.

IV. Historical Impact and Legacy

The administrative divisions of the Jiannan Circuit directly influenced the later Song Dynasty structure of the "Four Routes of Chuanxia," from which the name "Sichuan" eventually originated. Its geographical isolation, particularly the Sichuan Basin, formed a natural defensive barrier in the era of cold weapons, a strategic value that persisted from the Five Dynasties through the early Song. Modern landmarks like Chengdu's Jiannan Avenue, Mianyang's Jiannan Road, and the famous Jiannan Chun liquor preserve the historical memory of the Tang Dynasty's Jiannan Circuit.