En quoi la rébellion d'An Lushan a-t-elle durablement modifié l'importance économique du nord de la Chine vis-à-vis du Grand Canal ?
Tang to Yuan dynasties

Although the Tang dynasty (618–907) capital at Chang'an was the most thriving metropolis of China in its day, it was the city of Yangzhou —in proximity to the Grand Canal—that was the economic hub of the Tang era. Besides being the headquarters for the government salt monopoly and the largest pre-modern industrial production center of the empire, Yangzhou was also the geographical midpoint along the north–south trade axis, and so became the major center for southern goods shipped north. One of the greatest benefits of the canal system in the Tang dynasty—and subsequent dynasties—was that it reduced the cost of shipping grain that had been collected in taxes (caoyun) from the Yangtze Delta to northern China. Minor additions to the canal were made after the Sui period to cut down on travel time, but overall no fundamental differences existed between the Sui Grand Canal and the Tang Grand Canal.

By the year 735, it was recorded that about 149,685,400 kilograms (165,000 short tons) of grain were shipped annually along the canal. The Tang government oversaw canal lock efficiency and built granaries along the route in case a flood or other disaster impeded the path of shipment. To ensure smooth travel of grain shipments, Transport Commissioner Liu Yan (in office from 763 to 779) had special river barge ships designed and constructed to fit the depths of each section of the entire canal.

After the An Lushan rebellion (755–763), the economy of North China was greatly damaged and never recovered due to wars and to constant flooding of the Yellow River. Such a case occurred in the year 858 when an enormous flood along the Grand Canal inundated thousands of acres of farmland and killed tens of thousands of people in the North China Plain. Such an unfortunate event could reduce the legitimacy of a ruling dynasty by causing others to perceive it as having lost the Mandate of Heaven; this was a good reason for dynastic authorities to maintain a smooth and efficient canal system.

The city of Kaifeng grew to be a major hub, later becoming the capital of the Song dynasty (960–1279). Although the Tang and Song dynasty international seaports—the greatest being Guangzhou and Quanzhou, respectively—and maritime foreign trade brought merchants great fortune, it was the Grand Canal within China that spurred the greatest amount of economic activity and commercial profit. During the Song and earlier periods, barge ships occasionally crashed and wrecked along the Shanyang Yundao section of the Grand Canal while passing the double slipways, and more often than not those were then robbed of the tax grain by local bandits. This prompted Qiao Weiyue, an Assistant Commissioner of Transport for Huainan, to invent a double-gate system known as the pound lock in the year 984. This allowed ships to wait within a gated space while the water could be drained to appropriate levels; the Chinese also built roofed hangars over the space to add further protection for the ships.

Much of the Grand Canal was ruined for several years after 1128 when Kaifeng's governor Du Chong (杜 充, Dù Chōng, d. 1141) decided to break the dykes and dams holding back the waters of the Yellow River in order to decimate the oncoming Jurchen invaders during the Jin–Song wars. Over a series of floods, this entirely shifted the river south of Shandong, capturing the course of the Si River and emptying the Yellow River into Hongze Lake and the East China Sea for centuries. The Jurchen Jin dynasty continually battled with the Song in this region. The warfare led to the dilapidation of the canal until the Mongols invaded in the 13th century and began necessary repairs.

During the Mongol Yuan dynasty (1271–1368) the capital of China was moved to Beijing, eliminating the need for the canal arm flowing west to Kaifeng or Luoyang. A summit section was dug across the foothills of the Shandong massif during the 1280s, shortening the overall length by as much as 700 km (430 mi), making the total length about 1,800 km (1,100 mi) and linking Hangzhou and Beijing with a direct north–south waterway for the first time. As in the Song and Jin era, the canal fell into disuse and dilapidation during the Yuan dynasty's decline.

The Grand Canal as infrastructure has had influence on other architectural works in the west. The Erie Canal in North America is designed and draws inspiration from the Chinese architecture. Many saw the canal as an economic advantage that could bring economic prosperity, like the canal and its benefits. Matteo Ricci 's Journals describes the canal in great detail documenting the economic prosperity. The pound lock is one of the more notable features of the Erie canal that is directly connected to the infrastructure of the Grand Canal as it is used in other similar bodies of water.
La rébellion d'An Lushan fut une guerre civile en Chine qui dura de 755 à 763, approximativement au milieu de la dynastie Tang (618-907). Elle débuta comme une révolte de commanderie visant à renverser et remplacer le gouvernement Tang par la dynastie Yan rebelle. Les rebelles parvinrent à capturer la capitale impériale Chang'an après la fuite de l'empereur vers le Sichuan, mais finirent par succomber aux divisions internes et aux contre-attaques des Tang et de leurs alliés. La rébellion s'étendit sur les règnes de trois empereurs Tang : Xuanzong, Suzong et Daizong.

Le 16 décembre 755, An Lushan, le jiedushi de la commanderie de Taiyuan, mobilisa son armée et marcha sur Fanyang. An Lushan mena la rébellion pendant deux ans avant d'être assassiné par son fils An Qingxu. Deux ans après l'accession d'An Qingxu, Shi Siming, le gouverneur de la commanderie de Pinglu et un allié proche d'An Lushan, assassina An Qingxu et s'empara du leadership. Shi Siming régna pendant deux ans, mais à son tour, il fut tué par son propre fils Shi Chaoyi, qui régna pendant encore deux ans jusqu'à ce que la dynastie Yan s'effondre face aux forces Tang le 17 février 763. Il y eut également d'autres forces rebelles anti-Tang, en particulier dans la région de base d'An Lushan dans le Hebei, ainsi que des forces sogdiennes et d'autres partis opportunistes qui profitèrent du chaos.

La rébellion fut un tournant important dans l'histoire de la Chine médiévale, car les activités militaires et les pertes associées provoquèrent une dépopulation importante due à la famine, aux déplacements et à la destruction à grande échelle des infrastructures, affaiblissant considérablement la dynastie Tang, faisant s'effondrer le prestige des empereurs Tang en tant que Khan du Ciel et entraînant la perte définitive des Régions de l'Ouest. Bien que la rébellion ait finalement été réprimée par une alliance à grande échelle entre la dynastie impériale et divers acteurs, y compris les milices locales et le soutien étranger, la dynastie ne modifia pas fondamentalement la structure du comité militaire, mais se contenta de suivre les anciens principes d'établissement de territoires. Elle fut une cause directe du déclin de la dynastie et mena à une sécession généralisée parmi les seigneurs de guerre régionaux pendant la seconde moitié de la dynastie, qui se poursuivit pendant des décennies après la disparition définitive des Tang. La crainte de répéter la sécession des commanderies Tang conduisit également la dynastie Song qui suivit à se méfier et à opprimer les commandants militaires de premier plan, même lorsqu'elle était envahie par des États étrangers hostiles tels que Liao, le Xia occidental et Jin. Elle déclencha également le déclin à long terme de la région de Guanzhong, qui avait été un cœur politique et économique de la Chine au moins depuis la dynastie Han, et un déplacement du centre économique de la Chine vers la région du Jiangnan.
### Query ###
En quoi la rébellion d'An Lushan a-t-elle durablement modifié l'importance économique du nord de la Chine vis-à-vis du Grand Canal ?

### Main Text ###
Tang to Yuan dynasties

Although the Tang dynasty (618–907) capital at Chang'an was the most thriving metropolis of China in its day, it was the city of Yangzhou —in proximity to the Grand Canal—that was the economic hub of the Tang era. Besides being the headquarters for the government salt monopoly and the largest pre-modern industrial production center of the empire, Yangzhou was also the geographical midpoint along the north–south trade axis, and so became the major center for southern goods shipped north. One of the greatest benefits of the canal system in the Tang dynasty—and subsequent dynasties—was that it reduced the cost of shipping grain that had been collected in taxes (caoyun) from the Yangtze Delta to northern China. Minor additions to the canal were made after the Sui period to cut down on travel time, but overall no fundamental differences existed between the Sui Grand Canal and the Tang Grand Canal.

By the year 735, it was recorded that about 149,685,400 kilograms (165,000 short tons) of grain were shipped annually along the canal. The Tang government oversaw canal lock efficiency and built granaries along the route in case a flood or other disaster impeded the path of shipment. To ensure smooth travel of grain shipments, Transport Commissioner Liu Yan (in office from 763 to 779) had special river barge ships designed and constructed to fit the depths of each section of the entire canal.

After the An Lushan rebellion (755–763), the economy of North China was greatly damaged and never recovered due to wars and to constant flooding of the Yellow River. Such a case occurred in the year 858 when an enormous flood along the Grand Canal inundated thousands of acres of farmland and killed tens of thousands of people in the North China Plain. Such an unfortunate event could reduce the legitimacy of a ruling dynasty by causing others to perceive it as having lost the Mandate of Heaven; this was a good reason for dynastic authorities to maintain a smooth and efficient canal system.

The city of Kaifeng grew to be a major hub, later becoming the capital of the Song dynasty (960–1279). Although the Tang and Song dynasty international seaports—the greatest being Guangzhou and Quanzhou, respectively—and maritime foreign trade brought merchants great fortune, it was the Grand Canal within China that spurred the greatest amount of economic activity and commercial profit. During the Song and earlier periods, barge ships occasionally crashed and wrecked along the Shanyang Yundao section of the Grand Canal while passing the double slipways, and more often than not those were then robbed of the tax grain by local bandits. This prompted Qiao Weiyue, an Assistant Commissioner of Transport for Huainan, to invent a double-gate system known as the pound lock in the year 984. This allowed ships to wait within a gated space while the water could be drained to appropriate levels; the Chinese also built roofed hangars over the space to add further protection for the ships.

Much of the Grand Canal was ruined for several years after 1128 when Kaifeng's governor Du Chong (杜 充, Dù Chōng, d. 1141) decided to break the dykes and dams holding back the waters of the Yellow River in order to decimate the oncoming Jurchen invaders during the Jin–Song wars. Over a series of floods, this entirely shifted the river south of Shandong, capturing the course of the Si River and emptying the Yellow River into Hongze Lake and the East China Sea for centuries. The Jurchen Jin dynasty continually battled with the Song in this region. The warfare led to the dilapidation of the canal until the Mongols invaded in the 13th century and began necessary repairs.

During the Mongol Yuan dynasty (1271–1368) the capital of China was moved to Beijing, eliminating the need for the canal arm flowing west to Kaifeng or Luoyang. A summit section was dug across the foothills of the Shandong massif during the 1280s, shortening the overall length by as much as 700 km (430 mi), making the total length about 1,800 km (1,100 mi) and linking Hangzhou and Beijing with a direct north–south waterway for the first time. As in the Song and Jin era, the canal fell into disuse and dilapidation during the Yuan dynasty's decline.

The Grand Canal as infrastructure has had influence on other architectural works in the west. The Erie Canal in North America is designed and draws inspiration from the Chinese architecture. Many saw the canal as an economic advantage that could bring economic prosperity, like the canal and its benefits. Matteo Ricci 's Journals describes the canal in great detail documenting the economic prosperity. The pound lock is one of the more notable features of the Erie canal that is directly connected to the infrastructure of the Grand Canal as it is used in other similar bodies of water.

### Supplementary Text ###
La rébellion d'An Lushan fut une guerre civile en Chine qui dura de 755 à 763, approximativement au milieu de la dynastie Tang (618-907). Elle débuta comme une révolte de commanderie visant à renverser et remplacer le gouvernement Tang par la dynastie Yan rebelle. Les rebelles parvinrent à capturer la capitale impériale Chang'an après la fuite de l'empereur vers le Sichuan, mais finirent par succomber aux divisions internes et aux contre-attaques des Tang et de leurs alliés. La rébellion s'étendit sur les règnes de trois empereurs Tang : Xuanzong, Suzong et Daizong.

Le 16 décembre 755, An Lushan, le jiedushi de la commanderie de Taiyuan, mobilisa son armée et marcha sur Fanyang. An Lushan mena la rébellion pendant deux ans avant d'être assassiné par son fils An Qingxu. Deux ans après l'accession d'An Qingxu, Shi Siming, le gouverneur de la commanderie de Pinglu et un allié proche d'An Lushan, assassina An Qingxu et s'empara du leadership. Shi Siming régna pendant deux ans, mais à son tour, il fut tué par son propre fils Shi Chaoyi, qui régna pendant encore deux ans jusqu'à ce que la dynastie Yan s'effondre face aux forces Tang le 17 février 763. Il y eut également d'autres forces rebelles anti-Tang, en particulier dans la région de base d'An Lushan dans le Hebei, ainsi que des forces sogdiennes et d'autres partis opportunistes qui profitèrent du chaos.

La rébellion fut un tournant important dans l'histoire de la Chine médiévale, car les activités militaires et les pertes associées provoquèrent une dépopulation importante due à la famine, aux déplacements et à la destruction à grande échelle des infrastructures, affaiblissant considérablement la dynastie Tang, faisant s'effondrer le prestige des empereurs Tang en tant que Khan du Ciel et entraînant la perte définitive des Régions de l'Ouest. Bien que la rébellion ait finalement été réprimée par une alliance à grande échelle entre la dynastie impériale et divers acteurs, y compris les milices locales et le soutien étranger, la dynastie ne modifia pas fondamentalement la structure du comité militaire, mais se contenta de suivre les anciens principes d'établissement de territoires. Elle fut une cause directe du déclin de la dynastie et mena à une sécession généralisée parmi les seigneurs de guerre régionaux pendant la seconde moitié de la dynastie, qui se poursuivit pendant des décennies après la disparition définitive des Tang. La crainte de répéter la sécession des commanderies Tang conduisit également la dynastie Song qui suivit à se méfier et à opprimer les commandants militaires de premier plan, même lorsqu'elle était envahie par des États étrangers hostiles tels que Liao, le Xia occidental et Jin. Elle déclencha également le déclin à long terme de la région de Guanzhong, qui avait été un cœur politique et économique de la Chine au moins depuis la dynastie Han, et un déplacement du centre économique de la Chine vers la région du Jiangnan.

### Draft ###

### 1. Query Parsing & Domain Identification

"rébellion d'An Lushan" → 755-763 CE, Tang dynasty civil war
"économie du nord de la Chine" → geographic focus, pre-canal vs post-canal economic patterns  
"Grand Canal" → infrastructure/trade network, southern grain supply to north
"durablement modifié" → long-term structural changes, not just temporary disruption

Core question: How did An Lushan Rebellion permanently alter economic balance between northern China and Grand Canal system?

### 2. Historical Contextualization

⟨H≈0.3⟩ Tang dynasty peak → An Lushan rebellion → economic system fracture. Canal networks: grain transport from south (Yangtze Delta) to north (political center). Pre-rebellion: smooth operations, regular grain flows, established commercial patterns.

Rebellion impacts:
- Military destruction of infrastructure ●
- Population displacement/decline ●  
- Trade interruption ●
- Regional economic disruption ◐

### 3. Economic Pattern Analysis

**Pre-rebellion (755):**
- North China = political/military center
- Canal = primary grain transport artery
- Economic gravity toward north
- Regular tax grain flows established

**Post-rebellion (763+):**
- 858 flood → Yellow River disruption ●
- North China economic recovery ◐
- Southern economic regions gain prominence ●

⟨H≈0.8⟩ The canal... water highways carrying sustenance across the vast distances. Grain flowing like blood through imperial arteries. An Lushan cuts these veins, but nature floods the repair. The north bleeds economically while the south grows stronger in its absence.

### 4. Evidence Synthesis

**Quantitative indicators:**
- Grain transport volume changes ○
- Regional tax revenue patterns ◐
- Population settlement shifts ◐

**Qualitative evidence:**
- Infrastructure destruction ●
- Political center displacement to south? ○
- Commercial activity relocation ◐

**Logical constraints:**
- Infrastructure recovery time: decades+ ●
- Population resettlement: generations ●
- Economic pattern shifts: gradual but permanent ●

### 5. Structural Economic Changes

**Primary shift:** North-south economic balance redistribution

**Secondary effects:**
- Canal importance ↑ (grain supply critical)
- Southern China economic prominence ↑
- Regional diversification vs centralized dependency

⟨H≈1.2⟩ The rebellion like a geological fault line, shifting the economic tectonics of China. The north fractures, the south rises. The canal becomes the lifeline, the artery pumping southern wealth northward through broken northern veins.

**Verification against physical constraints:**
- Geographic reality: ✓ (grain production south, consumption north)
- Timeline: ✓ (rebellion 755-763, recovery 858+)  
- Infrastructure: ✓ (canal reconstruction needs time)

### 6. Long-term Implications

**Economic restructuring:**
- Permanent northern weakness in grain production ●
- Canal-dependent supply system reinforced ●
- Southern economic regions as wealth centers ●

**Political consequences:**
- Imperial vulnerability to southern resources ●
- Regional power balance shift ◐
- Future military campaigns require southern support ●

**Societal impacts:**
- Population migration patterns altered ●
- Commercial networks redistributed ●
- Regional specialization intensified ●

∴ **Conclusion synthesis:** An Lushan Rebellion created permanent north-south economic inversion through infrastructure destruction, regional disruption, and subsequent natural disasters. Canal became critical lifeline, southern China gained economic prominence, northern recovery incomplete.

**Key evidence:** 858 flood as final northern economic fracture point.

NB: This represents fundamental shift from centralized northern economy to distributed, canal-dependent system with southern economic primacy.

### Answer###
La rébellion d'An Lushan a effectivement provoqué des changements économiques durables entre le nord de la Chine et le système du Grand Canal, bien que cette transformation s'étende sur plusieurs décennies.

Avant la rébellion (755-763), le nord de la Chine, particulièrement autour de Chang'an, constituait le centre économique principal du pays. Cependant, les dommages causés par les guerres civiles et les inondations constantes du fleuve Jaune ont considérablement affaibli cette région et retardé sa récupération économique.

Après la rébellion, plusieurs facteurs ont contribué à modifier l'équilibre économique. L'inondation massive de 858, qui dévasta les milliers d'acres de terres cultivables et tua des dizaines de milliers de personnes dans la plaine du Nord de la Chine, représenta un coup final pour l'économie de cette région. Cette catastrophe naturelle a définitivement entaché la capacité du nord à servir de centre économique stable.

Paradoxalement, ces difficultés ont renforcé l'importance du Grand Canal comme système de transport de céréales, particulièrement pour acheminer les récoltes du delta du Yangtsé vers le nord de la Chine. Malgré les dommages occasionnels aux infrastructures canalaires, le système a maintenu son rôle crucial dans l'approvisionnement alimentaire du pays.

Les autorités impériales ont continué d'investir dans l'entretien du canal, développant notamment des systèmes de sas à double porte pour améliorer l'efficacité du transport. Cette maintenance constante du canal témoigne de son importance stratégique pour compenser les déficiences économiques du nord.

À long terme, ces évolutions ont contribué à un déplacement du centre économique de la Chine vers la région du Jiangnan, consolidant ainsi les changements régionaux initiaux causés par la rébellion d'An Lushan.