Great Song Dynasty Writer

Chapter 36: Frozen Soil Can't Support Millet
“Almost impossible.”

Facing the old man's interested gaze, Lu Beigu said, "Times have changed. The Tubo of today is completely different from the Tubo of that time. Although Zuo Siluo was nominally the king of Tubo in his early years, he was actually a puppet in the hands of the Hehuang sect leader and powerful people. Although he has now become the true ruler of Qingtang Tubo through some tricks, he is still the leader of the tribal alliance, and he is good at self-defense but not aggressive enough."

"Thus, when the Qingtang Tubo fought against the Xia Kingdom, if they held their ground, they could often rely on their greater endurance of the harsh snowy environment to push back the enemy. However, if they took the initiative to attack, they would inevitably be defeated due to their independence and mutual distrust. The fundamental reason for this was that the Tsunami was unable to achieve centralization. Even if our dynasty traded with them, the tribes below them would reap the lion's share of the profits. Therefore, it was difficult for them to be driven into executing offensive strategies, which they were not adept at, at the risk of severing trade."

"What's more, our dynasty's northwest is full of strongholds and forts. Li Yuanhao couldn't even reach Chang'an, so it's even more impossible for Qingtang Tubo to do so."

The old man nodded, thinking that the young man's words made sense, and was not frightened by his sudden questioning.

From this point of view, this "Strategy for Protecting Against Summer" must have been written by the young man himself, otherwise he would not be able to answer these questions.

But the old man continued to press further, "But you also said that times have changed. Now Qingtang Tubo cannot fully centralize power and is not good at attacking. But how do you know that you can't do it in the future?"

Lu Beigu looked outside the hall.

The current situation is a bit complicated. Should I answer or not answer?

Li Pan's disappearance also made Lu Beigu a little undecided.

However, Li Pan's actions also verified the identity of the old man in front of him, that is, he was most likely not Zhang Fangping.

The reason why Lu Beigu made such a speculation was very simple. Li Pan was such a pragmatic person that he would definitely not miss the opportunity to visit Zhang Fangping and show his face. If this was really Zhang Fangping, he would definitely come in instead of letting Lu Beigu deal with it himself.

The old man was so difficult to deal with, asking questions one after another, which also showed that Li Pan should have known that the other party was not easy to deal with, so he deliberately avoided him.

But Lu Beigu had no way to avoid it, and taking a step back, no matter who the old man in front of him was, the fact that he could appear here showed that he had an extraordinary identity.

Therefore, for Lu Beigu who was brought here, it actually didn’t make much difference who he talked to.

Because no matter who he is facing or what questions are asked, he will try his best to answer.

However, the old man's question was really tricky, and even a bit argumentative.

But is this conjecture possible?

That's quite possible. Just as no one living in this era could have imagined that the Jurchens, a tiny tribe still struggling to fish and hunt in the deep mountains and forests of the Liao Kingdom's northeast, would, just a few decades later, overwhelm both the Liao and Song dynasties, two vast states. How can you be sure that if formal trade were to enrich the now-weak Qingtang Tubo, it wouldn't recapture the glory of Songtsen Gampo's time?
It is definitely wrong to infer the future based on the current situation. After all, if a powerful leader really comes out, he will first accumulate capital by submitting to the Song Dynasty through trade, and then integrate the internal affairs to complete centralization before expanding outward. Isn't this move by the Song Dynasty just nurturing a serious threat to itself?
Logically speaking, this topic has basically reached a dead end after being discussed here. After all, Lu Beigu cannot prove things that have not yet happened in the future.

However, Lu Beigu changed the subject.

"But the most important reason why I made this judgment is actually the climate."

The word "climate" actually exists in ancient times and is not a modern word.

"The Yellow Emperor's Classic of Internal Medicine·Suwen" wrote that "five days are called a period, and three periods are called a climate". From the Warring States Period to the Western Han Dynasty, "climate" began to be used as a general term to describe the cyclical changes of solar terms and phenology in a year. "The Book of Rites·Monthly Ordinances" records that "in the past, Duke Zhou made a time system, determined the twenty-four solar terms, divided them into seventy-two periods, and the rise of climate."

By the pre-Tang Dynasty, with the increasing number of climate records in agricultural texts like Qi Min Yao Shu, the term "climate" gradually evolved to encompass factors like precipitation and temperature. So the old man had no problem understanding this, but he was still curious about the term.

"Oh?"

He placed the policy paper on the table, a strange look flashing in his eyes as he asked, "That sounds interesting. What does that mean?"

"The 'Book of Tang: A Biography of Tibet,' compiled by Liu Shu of the Later Jin Dynasty, and the 'Tongdian: A Biography of Tibet,' compiled by Du You of the Former Tang Dynasty, not only describe the Tibetan system, laws, products, and customs, but also mention that during the reign of Songtsen Gampo, the snowfields were able to grow abundant crops and support hundreds of thousands of troops. Later, when I consulted the notes of the Former Tang Dynasty, I learned that this was during the 'warm period,' when the snowline had moved significantly higher than it does today, allowing the Tibetans to cultivate the snowfields."

"However, various notes from the late Tang and Five Dynasties record that since the end of the Tang Dynasty, the north has become increasingly cold and snowy, with many poplar trees in the western regions dying, and the snow line in the snowfields has moved lower again."

"How can frozen soil support crops? The cultivated land on the snowy plains can only support a million households at best. If we expand outward, we will have to endure long expeditions without local supplies, and it will be impossible to sustain the population."

"That's a novel idea."

The old man was greatly surprised, and then he continued to ask with interest, "Then how long will it take for the snow line on the snowfield to move back down again after it moves up? Have you studied this?"

"As far as the snowline of the snowfield is concerned, there's currently no evidence of this, as you mentioned before. The Central Plains only learned of permanent human habitation and trade in the snowfields during the Southern and Northern Dynasties, when they interacted with the Tuyuhun. There's no record of it before then, so it's likely uninhabitable."

Lu Beigu then said, "But if we look at the historical records of the Central Plains, we can get a glimpse of some clues."

The old man's eyes were filled with surprise, and he tapped the table with his fingers. "So, you are using the phenology recorded in historical books to infer the temperature of the climate?"

"Exactly."

Lu Beigu nodded and said, "The Book of the Later Han records that 'in the winter of the sixth year of Emperor Ling's Guanghe reign, there was a severe cold snap. The ice in the wells of Beihai, Donglai, and Langya was over a foot thick.' And the Records of the Three Kingdoms records that 'in the tenth month of the winter of the sixth year of Emperor Huangchu, the emperor traveled to the old city of Guangling and inspected the troops by the river. There were over a hundred thousand soldiers and banners stretching for hundreds of miles. It was a very cold year, and the waterways were frozen. Boats could not enter the river, so they were forced to return.' This shows that by the end of the Han Dynasty and the Three Kingdoms period, it was extremely cold both north and south of the Huai River."

"However, the Book of Song and the Book of Southern Qi record that there were often droughts and no snow in winter between the north and south of the Huai River. The difference in cold and warm weather is clearly evident."

"Thus, from the end of the Han Dynasty to the Southern Dynasties of Song and Qi, the climate began to warm. Then, from the Eastern and Western Wei Dynasties to the early Tang Dynasty, the climate gradually became warmer, the snowfields melted, and the Tubo became stronger. But by the late Tang and Five Dynasties, it turned cold again. This cycle of growth and decline seems to follow a regular pattern."

"Heaven's laws are constant; they don't exist for the sake of Yao or perish for the sake of Jie. Tubo's prosperity was due to the fertile soil created by the warm season; its decline was due to the arrival of the cold season, when the frozen soil became difficult to cultivate. Therefore, I believe that although Qingtang Tubo now controls the Hehuang region, its agricultural foundation has been lost. Even with a powerful ruler, it would be difficult to restore the glory of Songtsen Gampo."

A gust of wind suddenly blew outside the window, rippling the water of the Maha Pond and swaying the lotus flowers.

"Interesting! Very interesting!"

The old man looked at Lu Beigu approvingly and said, "Your theory of 'cold period' and 'warm period' is in line with the ancient theory of 'Five Movements and Six Qi'. However, the ancients often said that celestial phenomena responded to human affairs, while you use cold and warm periods to discuss prosperity and decline. This is quite novel."

"If this is the case, then the northern barbarians also prospered and declined due to changes in temperature?"

(End of this chapter)