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[The various factors behind the fall of the Tang dynasty also answer another question:
Why did the Song dynasty not consider Chang'an or Luoyang as its capital?
The most direct reason is that after the chaos of the late Tang and the Five Dynasties and Ten Kingdoms period, these two places had been completely battered.
Take Luoyang as an example. In the early Northern Song, the registered civilian households numbered only twenty thousand, which translated to just over one hundred thousand people in total.
Such a population and level of productivity were utterly insufficient to support a central machine like Bianjing.
The fundamental reason lay in a problem that had already become prominent during the Tang dynasty: grain transport.
Or, to put it more bluntly: food.
No matter how powerful Tang was, did the emperor not still have to obediently run to the Eastern Capital, Luoyang, to beg for food?
And where did Luoyang's grain come from? From waterway transport, shipping rice from the southeast.
And where did Luoyang's grain come from?
From the southeast—transported by water.
Song scholars observed the same problem:
"Though Guanzhong is famed as fertile land, its territory is narrow. Its yield cannot supply the capital nor safeguard against flood or drought; thus grain must constantly be shipped from the southeast."
After the Tang collapsed, the Central Plains underwent a full system update:
• The "rice can be grown north of the Yellow River" bug was patched.
• Nomadic enemies began spawning regularly.
• The "northern winters don't snow" bug was fixed—heavy snowfall now arrived on time and in full.
• The Yellow River's shipping capacity was nerfed.
• Guanzhong's grain output was reduced.
• Luoyang entered a state of abandonment.
Under this relentless series of debuffs, the southern regions—already showing early promise during the Tang—became even more critical.
After all, the north had to endure severe cold and the threat of nomadic incursions, making its production environment extremely harsh.
The south faced no foreign cavalry, and the overall fluctuations in climate had a comparatively limited impact there. Thus, the southward shift of the economic center became inevitable.
Under such circumstances, if Zhao Kuangyin had suddenly lost his head and slapped his forehead, forcibly setting the capital in Guanzhong, the scene of the Song dynasty would be unthinkable:
Finance and grain depending on the Jianghuai region, border defense against enemies relying on Hebei, canal transport transit centered on Bianliang, and the political center sitting in Guanzhong.
If things were really played that way, the Song would probably have collapsed on its own without needing the Donkey Cart Emperor to intervene.
In fact, the rise of Bianjing, or Kaifeng, was itself related to the Tang dynasty.
Before the An Lushan Rebellion, Guanzhong was Tang's political and military center, while financial and grain support was jointly provided by Jianghuai and Hebei. These two regions were connected by the Yongji Canal and the Tongji Canal. Luoyang lay right between them, making it an ideal choice for the Eastern Capital.
The An Lushan Rebellion devastated Hebei's livelihood and bred mutual suspicion between local regions and the central court. As a result, one of Tang's two pillars was directly severed. In the mid to late Tang, nearly all financial resources relied on Jianghuai, and the Tongji Canal became Tang's sole lifeline.
Under these conditions, Bianzhou became a new balance point for maintaining canal security and eventually replaced Luoyang's position.
In truth, the Northern Song learned from Tang's lessons. Establishing the capital in Bianjing effectively stacked military, political, financial, and canal transport nodes together for easier central control.
In Zhao Kuangyin's early years, he may indeed have considered moving the capital to Luoyang. After all, in 972, Bianliang's annual canal transport was only five hundred thousand shi, making relocation losses manageable.
But ten years later, annual transport surged to four million shi, and twenty years later rose again to six million shi. The immense pressure made relocating the capital equivalent to cutting into the heart, where a single misstep meant self destruction.
However, the later long march south by the Jin dynasty also proved that what Zhao Guangyi said about choosing virtue over terrain was nothing more than empty talk.]
"This… these two canals were built by human effort?"
Liu Bei sucked in a sharp breath.
The map was clearly marked. The northern canal began at Zhuo Commandery, linked the Yellow River, and connected southward to Jianghuai. The sheer scale of such a project was staggering even to imagine.
How much manpower and material would this require? That Tang could build such a massive work. Why had the later generations never mentioned it?
"This was not Tang's doing, but Sui's achievement," Pang Tong shook his head.
A closer look made it clear. Each segment of the canal had a time marker beside it, likely indicating its completion date.
Comparing this with the temperature fluctuation chart made it obvious that this long canal was a hydraulic project initiated by the short lived Sui dynasty.
"Still, this canal truly is…" Pang Tong struggled to find the right words.
The diagram itself was fairly simple. Kongming quickly copied it down, then frowned and pointed section by section as his own thoughts took shape.
"The merit of this canal should lie in integrating earlier works and dredging old channels."
His long index finger tapped the Han Canal.
"This canal was excavated during the time of King Fuchai of Wu, and at that time the Yellow Canal was also dug, connecting the Si and Ji rivers."
His finger then moved upward.
"Cao Cao also opened the White Canal to connect the Yellow River and the Qing River. For his campaign against the Wuhuan, he opened the Pinglu and Quanzhou canals."
After a brief tally, Kongming still admitted,
"That Sui could link old canals, dig new ones, and connect north and south can truly be called a magnificent achievement across ages."
"Only…" Kongming hesitated, then shook his head without finishing.
Kongming might hesitate, but Zhang Fei certainly did not. He slapped Ma Chao so hard that Ma Chao jumped up, clutching his leg, while Zhang Fei spoke boldly.
"What's there for the strategist to avoid saying? Even I can see it clearly. This Sui probably dug canals until it dug itself to death."
After all, speaking reasonably, Zhang Fei had personally taken part in dredging waterways in Chengdu, and in his hometown of Zhuo Commandery he had also dug canals before.
Ordinary rivers and canals were already exhausting enough, let alone an unprecedented canal spanning north and south. The number of conscripted laborers was probably beyond anything they could imagine.
Fa Zheng also felt deeply moved and spoke softly.
"The fall of Sui does not quite match what the later generations said about climate change."
"From the chart, one can see that when Sui was founded, it no longer faced the severe cold of chaotic times. It even had a period of rest and recovery known as the Kaihuang era. The climate gradually warmed, already showing signs of a flourishing age."
"Yet the dynasty lasted less than fifty years, fell in its second generation, and the posthumous title of the fallen ruler was Yang, something unheard of in antiquity."
Ma Chao rubbed his leg and grew curious.
"What does the title Yang mean?"
Jian Yong was just about to explain when Zhang Fei laughed loudly.
"That's easy. Indulgent in pleasures and neglecting governance is called Yang."
"In other words, Emperor Yang spent all day in the inner palace and never attended court."
"Uh…" Jian Yong nearly stumbled. Yide, did you ignore all the other explanations of the title and only read the words indulgent in pleasures?
He really did read books, just selectively.
Ma Chao was genuinely startled by Zhang Fei's knowledge, then spoke without thinking.
"Such behavior truly makes us envious… hateful beyond endurance!"
Seeing Jian Yong's gaze sweep over, Ma Chao immediately straightened up righteously.
"If all emperors behaved like this, how could the people not hate it?"