By the time the carriage returned to the city, night was already falling. They made it through the gates of Chang’an just before they closed.
Having successfully won over Zhang Zheng and the others, the heavy weight on Jiang Congyan’s heart eased slightly. With trusted guards at her side, even if she were to marry into Mobei, she would at least have some protection—and more freedom to act.
What she had said earlier was not merely to secure their loyalty; she had meant every word. If they were unwilling to follow her north, she would not force them or hold it against them. In the distant and desolate lands beyond the frontier, what she needed were people she could trust completely.
Once their decision to go north together was settled, Jiang Congyan immediately wrote a letter to her grandfather in Liangzhou, explaining the situation of Zhang Zheng and the others, and asking him to take care of their families. She also had the soldiers write letters home. This parting might last years—who knew when they would return to the Central Plains?
In addition, she took out money from her private funds and distributed it among the soldiers so they could send it back to their families.
After all this, the men felt even more deeply indebted to her, wishing they could repay her with their lives.
By the time she returned to the Prince of Chu’s residence, night had fully fallen. In the deep blue sky, a slender crescent moon cast a faint glow, surrounded by countless stars.
Chang’an was a city upon the earth; the earth itself was but a star in the heavens.
The entire city lay hushed in the boundless night. Only the watchtowers and a few grand mansions still flickered with candlelight. Jiang Congyan’s room was lit with several candles, bright as day.
After a long day of rushing about, she ate a simple meal of porridge and cakes, but did not rest. Instead, she had Ruolan bring out a chest of account books and sat cross-legged on the couch, flipping through them one by one.
In public, her etiquette was impeccable; in private, she was more relaxed. After all, kneeling properly at all times was hardly humane.
She had been frail as a child, and her grandfather had never demanded strict decorum of her—he only wished for her to grow up healthy and happy. It was only when she grew older and needed to socialize that she seriously learned etiquette from Ruolan.
Ruolan, like the Marquis of Liangzhou, only cared for her happiness, and thus never restrained her in private, allowing Jiang Congyan to become even more free-spirited.
Under the candlelight, Jiang Congyan carefully examined the account books—records of what she had built over the past few years.
Some were originally properties of the Prince of Chu’s estate, which had flourished under her management—such as the farmland outside the capital and several residences.
Others she had transformed—like Guiyuan Distillery, today’s Heqing Silver House, as well as several herbal medicine shops and eateries.
These businesses were not just for profit—they were her laboratories.
Alcohol, she knew, had powerful disinfectant properties for wounds on the battlefield. But limited by the technology of the time, even with theoretical knowledge, large-scale production was difficult. Repeated distillation could yield high-concentration alcohol, but at enormous cost in labor and resources for very little output—hardly practical.
So she could only experiment slowly, improving efficiency within limited conditions.
Even so, when the Marquis of Liangzhou discovered how effective her distilled alcohol was in preventing infection, his eyes lit up with excitement and praise.
As for the silver shop—she had originally intended to use it to explore iron-smelting techniques. But she soon realized she had been naïve.
At present, metallurgy was transitioning from the fining method to the cast-steel method. While the former produced high-quality steel, it was complex and required great skill, making mass production impossible. The latter could improve quality while simplifying the process—if successful, it would greatly enhance productivity.
But a silver shop was far removed from true ironworking. The scale of engineering and equipment required was far beyond her means. And conducting such experiments in Liangzhou? Impossible. The Emperor had countless spies—if he learned the Zhang family was researching metallurgy, he would likely accuse them of rebellion the very next day.
So the matter remained stalled. She could only conduct small-scale tests in workshops, carefully verifying theory, waiting for the right moment in the future. Even then, she had to proceed with extreme caution.
Medicine, however, faced fewer restrictions—and that gave her some satisfaction.
In this era, physicians were of low status and often associated with witchcraft. Many common people could not distinguish between shamans and doctors, relying on talisman water and ritual dances to cure illness.
Because of her frail health, the Zhang family had sought out renowned physicians—and thus invited Zhang Yuan.
The moment Jiang Congyan heard his name, she knew he could not be allowed to leave Liangzhou.
Historically, Zhang Yuan was a great physician, especially skilled in internal medicine. It was said he was a descendant of Zhang Zhongjing, the great medical sage who authored Treatise on Cold Damage and Miscellaneous Diseases, establishing the principles of diagnosis and treatment that became the foundation of traditional medicine.
Zhang Yuan had originally intended to continue traveling after treating her, but the Zhang family persistently persuaded him to stay—offering gold, rare medicines, even invoking their shared surname.
Still, he refused—until Jiang Congyan spoke with him.
She told him about modern medicine—about anatomy and molecular biology. These ideas were utterly revolutionary. While anatomy had some precedent, molecular theory was beyond imagination.
At first, Zhang Yuan could hardly believe it. But as certain aspects were verified, he was stunned, feeling as though his entire world had been overturned.
In truth, Jiang Congyan was bluffing. Though she had learned some medical knowledge during her long illness, she had never practiced medicine, not even conducted experiments. Yet this did not stop her from using her fragmentary knowledge to astonish a man from a thousand years ago.
Later, she even had craftsmen polish a piece of crystal into a magnifying lens. After seeing it, Zhang Yuan became completely fascinated—and stayed.
She had not kept him for her own treatment, but to see if modern medicine could take root.
Sometimes, the birth of a new idea is far more important than its completion. Once the seed is planted, it may one day grow into a towering tree.
Yet years later, as the land grew ever more turbulent, even mighty Liangzhou could not stand alone. After the fall of Great Liang, it became isolated—like a lone boat on the sea—eventually swallowed by the tides.
“Of the Zhang clan, all three hundred and sixty-one souls perished.”
Ten brief words in the annals—yet they told a tragic end.
Jiang Congyan feared she might not be able to change history. That Liangzhou would one day be consumed by war. All she could do was try—again and again—using her limited knowledge to add even a single brick, a single tile, so that when the flood came, there might remain a few broken walls to shelter those who survived.
Zhang Yuan remained in Liangzhou, continuing his medical work and compiling practical methods for military use. He had two sons—Zhang Fu and Zhang Cheng—both of whom inherited his medical skills. Zhang Fu, especially, was interested in Jiang Congyan’s “modern medicine,” and had followed her to the capital two years earlier, staying in one of her herbal shops. They often discussed ideas together.
This time, Jiang Congyan intended to bring him along.
“Aunt, tomorrow send word to Zhang Fu—ask whether he is willing to go north with me. Just ask; do not pressure him,” she said.
Zhang Fu was not like Zhang Zheng and the others—he was not a hereditary retainer of Liangzhou.
Then Jiang Congyan turned to the last set of accounts—
These were businesses that could not be brought into the light.