Chapter 36: Frozen Soil Cannot Bear Grain

“Almost impossible.”

Facing the old man’s intrigued gaze, Lu Beigu said: “Times have changed. The Tibet of today is utterly different from the Tibet of old. Though Ngasong Tsanpo was nominally king of Tibet in his early years, he was in fact a puppet in the hands of the river-hill religious leaders and powerful clans. Now, through various maneuvers, he has become the true Zanpu ruling Qingtang Tibet, but fundamentally he remains merely the leader of a tribal alliance—capable of rallying tribes for defense, but lacking the strength for offensive action.”

“Thus, when Qingtang Tibet fights the Xia state, it often succeeds in defense by enduring the brutal snowland environment to drive off invaders. But whenever it launches an offensive, it is inevitably crushed due to disunity and mutual distrust among the tribes. The root cause is Ngasong Tsanpo’s inability to centralize power. Even when our state trades with them, the bulk of the profits go to the lower tribes, so these tribes are unlikely to be coerced into launching offensives—strategies they are ill-suited for—risking the severance of trade.”

“Moreover, our state’s northwest is dotted with garrisons and fortresses. Even Li Yuanhao failed to reach Chang’an. How could Qingtang Tibet possibly succeed?”

The old man nodded. The boy spoke sense—he had not been intimidated by the sudden challenge.

It seemed clear now that this essay, “Strategies Against Xia,” must have been written by the boy himself; no one else could have answered these questions.

But the old man pressed further: “Yet you yourself admitted times have changed. Today’s Qingtang Tibet cannot fully centralize power, nor is it skilled in offense. How can you be certain it won’t achieve that in the future?”

Lu Beigu looked out the hall.

The current situation was complicated. Should he answer or not?

Li Pan’s absence also left Lu Beigu uncertain.

Yet Li Pan’s behavior indirectly confirmed the old man’s identity—he was almost certainly not Zhang Fangping.

The reason for Lu Beigu’s deduction was simple: Li Pan, a pragmatist through and through, would never pass up the chance to pay homage to Zhang Fangping and gain face. If this were truly Zhang Fangping, Li Pan would have entered himself, not left Lu Beigu to face the old man alone.

And the old man’s persistent, relentless questioning suggested Li Pan knew this man was dangerous—hence his deliberate avoidance.

But Lu Beigu had no escape. Moreover, regardless of who this old man was, his presence here alone proved his status was extraordinary.

Thus, for Lu Beigu, who had been brought here, it made little difference whom he spoke to.

For whoever he faced, whatever question was asked, he had to answer to the best of his ability.

Yet this question from the old man was exceptionally tricky, almost deliberately combative.

But was such a possibility conceivable?

It certainly was. Just as people of this era never imagined the Jurchens, then struggling in the remote forests of northeastern Liao, a weak and insignificant tribe, would within decades bring down both the Liao and Song empires. On what grounds can you assert that if formal trade fattens today’s weak Qingtang Tibet, it won’t revive the glory of Songtsen Gampo’s era?

Judging the future by present conditions is certainly flawed. After all, if a true ruler emerged, first submitting to Great Song to accumulate wealth through trade, then consolidating internal power before expanding outward—wouldn’t our state merely be nurturing another grave threat?

Logically, this debate should end here in deadlock, since Lu Beigu cannot prove events yet to come.

Yet Lu Beigu shifted his tone.

“But my judgment rests primarily on one crucial factor: climate.”

The term “climate” has ancient origins—it is not a modern word.

The Emperor Neijing’s Suwen states: “Five days constitute a hou; three hou constitute a qi.” By the Warring States and Western Han periods, “qi” and “hou” were combined into “qihou,” describing the cyclical changes of seasonal phases and phenology. The Liji’s Yue Ling commentary records: “Formerly, Duke Zhou established the seasonal system, fixing the twenty-four solar terms and seventy-two hou—thus the origin of qihou.”

By the early Tang, as agricultural texts like Qimin Yaoshu increased records of climate, the term “qihou” gradually evolved to encompass precipitation, temperature, and other elements.

Thus, the old man had no difficulty understanding it—but he still felt curious.

“Oh?”

He set the essay down on the table, a flicker of interest in his eyes, and asked: “That sounds intriguing. Explain.”

“The Tangshu’s ‘Tibetan Biography,’ compiled by Liu Xu of Later Jin, and Du You’s Tongdian ‘Tibetan Biography,’ besides detailing Tibetan governance, laws, products, and customs, mention that during Songtsen Gampo’s time, the snowlands could grow abundant grain, sustaining hundreds of thousands of troops. Later, after consulting Tang-era notebooks, I learned this coincided with a ‘warm period,’ when the snowline had risen far above today’s level, allowing Tibetans to expand cultivation onto the snowlands.”

“Yet various late Tang and Five Dynasties records note that since the end of the Tang, the north has grown steadily colder, with constant snowstorms, widespread death of poplars in the Western Regions, and the snowline retreating once more.”

“How can frozen soil sustain grain? Today’s snowland farmland can barely support a million households. If they attempt expansion, long-distance campaigns without local supply cannot be sustained.”

“This is a novel claim.”

The old man was greatly surprised and pressed further: “How long would it take for the snowline to rise again and then retreat? Have you studied this?”

“As for the snowline alone, there is currently no evidence, as you previously noted. The Central Plains only learned of human habitation and trade on the snowlands during the Northern and Southern Dynasties, through contact with the Tuyuhun. Before that, there are no records—likely because the land was uninhabitable.”

But Lu Beigu added: “Yet if we examine Central Plain historical records, we may discern some patterns.”

The old man’s surprise deepened; his fingers tapped lightly on the table: “So you infer climate fluctuations from historical records of phenology?”

“Precisely.”

Lu Beigu nodded: “The Hou Hanshu records: ‘In the sixth year of Emperor Ling’s Guanghe era, winter was bitterly cold; ice in wells of Beihai, Donglai, and Langye reached over a foot thick.’ The Sanguozhi records: ‘In the tenth month of the sixth year of Huangchu, the Emperor toured the ruins of Guangling, inspected troops by the river, with over 100,000 soldiers and banners stretching hundreds of li. That year was bitterly cold; rivers froze, boats could not sail, and he turned back.’ Clearly, by the end of the Han and Three Kingdoms, the region north and south of the Huai River was extremely cold.”

“Yet the Songshu and Nan Qishu record that winters in the Huai region often lacked snow and suffered drought. The difference in warmth and cold is evident.”

“Thus, from the end of the Han through the Southern Dynasties of Song and Qi, the world’s climate shifted from cold to warmth. Later, from the Eastern and Western Wei to the early Tang, warmth increased further; snow melted, Tibet grew strong. Then, in late Tang and the Five Dynasties, it turned cold once more. This ebb and flow, this cyclical pattern, appears to follow a discernible rhythm.”

“Heaven’s way is constant—it does not endure for Yao nor perish for Jie. Tibet’s prosperity arose from the warm period’s fertile land; its decline came with the cold period’s frozen soil, unfit for farming. Hence, I believe that though Qingtang Tibet now holds the river-hill region, its agricultural foundation is lost. Even a capable ruler cannot restore the glory of Songtsen Gampo’s time.”

A sudden wind stirred outside; the waves of Mohe Pond rippled, lotus flowers swayed.

“Fascinating! Most fascinating!”

The old man regarded Lu Beigu with approval: “Your ‘cold period’ and ‘warm period’ theory echoes the ancients’ ‘Five Phases and Six Qi’ doctrine. Yet the ancients spoke of celestial phenomena reflecting human affairs; you use warmth and cold to explain rise and fall—truly original.”

“If so, does this also explain the rise and fall of northern barbarians through climate shifts?”

(End of chapter)