Li Shimin sat behind his desk, a confidential intelligence report held loosely between his fingers. Chancellor Du Ruhui had placed it there moments ago. He read it once, then read it again, letting the words settle before he made his decision.
"Summon Pei Shiqing."
The arrival of the Japanese envoys had caught him completely off guard.
In his head, the strategic roadmap was already drawn. Military priorities came first. Crush the Tuyuhun kingdom, punch a hole through the Hexi Corridor, and project power deep into the Western Regions. Restoring the dominance of the ancient Han Dynasty sat at the very top of his agenda.
Everything else could wait. The Korean Peninsula was a problem for later. The Japanese archipelago was an afterthought. The scattered islands of the South China Sea were distant dreams, and the legendary resource-rich continents rumored to exist across the ocean were little more than fairy tales at this point.
Conquering any of those distant lands required one specific tool. The Tang Empire needed an invincible naval fleet.
The current state of the Tang navy was depressing. The shipyards in the Lingnan and Jiangnan circuits provided huge logistical support, yet even with all that wealth behind them, the fleet struggled just to launch operations against nearby Liuqiu. Expecting these fragile wooden boats to sail into the deep ocean and intimidate foreign barbarians was pure fantasy.
Because of this harsh reality, Li Shimin had deliberately hit pause on his maritime ambitions.
He took a three-pronged approach instead.
First, he established the Mathematics Academy in Chang'an. The scholars were tasked with studying classical mathematics, but more importantly, they were ordered to figure out how advanced mathematics could be applied to state administration and naval navigation.
Second, he recalled a large group of veteran naval commanders from the coast and mixed them with a group of brilliant young officers led by Liu Rengui. He locked them all in Chang'an for an intensive six-month crash course. They studied maritime law, analyzed foreign tribal customs, and learned how to read ocean currents and manipulate wind patterns. Once they graduated, they would return to the coast and take joint command of a reformed fleet.
Third, he gave Hou Junji a blank check. Old Hou assembled a specialized test fleet and drove experimental ships straight into rough waters, testing bizarre new sailing tactics and documenting every failure and success. That data would eventually form the foundation of an entirely new naval doctrine.
A diplomatic mission from Japan was nowhere in this meticulous plan. It felt entirely out of sequence.
According to the future history Li Shimin had learned, the Japanese were supposed to cower on their islands for years. They were only supposed to send envoys to the Tang court after getting crushed at the Battle of Baekgang. Why were they showing up now?
Li Shimin waved a hand and dismissed Du Ruhui. He ordered the Chancellor to dig up every detail about the incoming delegation.
Then he waited for his resident Japan expert.
If anyone in the Tang court understood that bizarre island nation, it was Pei Shiqing. The man was a relic of the previous Sui Dynasty. He had actually sailed across the eastern sea as an official envoy.
Wei Zheng had dug up the man's personnel file a while ago. Li Shimin read it and immediately promoted him. Pei Shiqing went from holding a comfortable desk job in the Bureau of Equipment to serving as the Director of the Palace Library, a position that gave him direct access to the Emperor.
Li Shimin had personally interviewed him shortly after the promotion. He grilled Pei Shiqing on Japanese geography, asked about local customs, and ordered the man to write a comprehensive book detailing everything he had seen across the ocean.
Now, the very first Japanese delegation of the Tang era was knocking on his door. Li Shimin took the most pragmatic route available.
He called the man who had actually been there.
The palace eunuchs moved with impressive speed. Pei Shiqing was escorted into the hall shortly after the summons was issued.
This was only the second time Li Shimin had met the man in person. The Emperor looked him up and down and could not help but silently approve.
The man was absolute prime material for a diplomat.
When representing the empire abroad, physical appearance was half the battle. Pei Shiqing passed that test with flying colors.
He was pushing fifty, yet he stood tall and straight. He possessed a commanding, masculine aura that was uniquely Han. He did not need to raise his voice to radiate authority. People naturally wanted to follow him.
He was strikingly handsome.
Of course, all that natural authority shattered the moment he faced the Emperor. Pei Shiqing bowed deeply and offered a crisp greeting.
"Your Majesty."
Li Shimin skipped the pleasantries and got straight to the point.
"Pei Qing. We have envoys from Japan. They have already crossed into the Hebei Circuit. What is your assessment?"
"They are here for our culture, Your Majesty. There is no other reason."
"Oh?" Li Shimin raised an eyebrow. "You sound very certain."
"I am." Pei Shiqing straightened. "After you summoned me last time, I did some private investigating during my days off. Back in the 6th Year of the Wude era, a group of Japanese monks finally packed their bags. These were men who had followed the original envoys to China during the Sui Dynasty. They spent years studying in our temples. 8 years ago, they boarded ships and went home."
"And?"
"And those monks have been home for 8 years now." Pei Shiqing folded his hands together. A confident smile touched his lips. "They have undoubtedly spent that entire time preaching about the overwhelming glory of our empire. The Japanese court wants to repeat history. They want to mimic the cultural exchanges of the Sui era. They admire our civilization, Your Majesty. They want to learn our ways."
Li Shimin leaned back in his chair. "So they come as students, not as threats."
"Exactly." Pei Shiqing's smile vanished, replaced by a look of deep disdain. "Though I would not flatter them with the word student. I walked their lands, Your Majesty. Their common people are absolute savages. They have no concept of basic etiquette. Their ruler is incredibly vulgar."
"Vulgar how?"
"She lacks basic decency." Pei Shiqing's lip curled. "She calls herself the Son of Heaven where the sun rises. It is the laughable arrogance of a frog sitting at the bottom of a well."
He took a step forward, his voice ringing with conviction.
"Your Majesty has punished the wicked. You captured Illig Qaghan and dragged him before your throne. The prestige of the Tang Empire echoes from the northern deserts all the way to Liaodong. These islanders will arrive trembling in fear. They will barely be able to stand beneath your heavenly aura. You simply need to decide what to give them, and what to withhold."
Li Shimin sat perfectly still.
But his brain completely stalled the moment Pei Shiqing said the words, "She lacks basic decency."
The Emperor stared at the diplomat's chiseled jawline.
His mind drifted away from statecraft.
After discovering Pei Shiqing's background, Li Shimin had deployed his secret police. He ordered the Hundred Riders to track down any surviving members of that original Sui diplomatic mission. He wanted a complete picture. He did not want to rely entirely on one man's perspective.
Too much time had passed. The spies could not find many surviving sailors or guards. However, they did bring back a highly amusing piece of tavern gossip.
The rumor was wild. It claimed that the local Japanese population was incredibly short. Most of the men barely reached 5 feet in height. When the Sui embassy arrived, the locals were terrified. The Han diplomats were all towering men over 6 feet tall with broad shoulders and booming voices. The islanders thought literal gods had walked off the boats.
The rumor got even better. The Japanese queen was supposedly so impressed by their genetics that she took drastic action. She reportedly sent her own royal daughter to the diplomatic guesthouse. Her goal was simple. She wanted to harvest some premium Han bloodlines to upgrade the royal family.
At the time, Li Shimin thought the report was absolute garbage. It sounded like drunken sailors bragging in a brothel.
Now, sitting in Ganlu Hall, he looked at Pei Shiqing. The man was tall, broad, and carved from marble. He carried himself like a hero from a romance novel.
Li Shimin blinked.
He actually understood the Japanese queen's logic now. If a whole boat full of guys who looked like this showed up on a primitive island, things were bound to get weird.
"Your Majesty?"
Pei Shiqing called out softly. He had finished his speech minutes ago. The Emperor was simply staring at his face with a very strange expression.
"Cough! Cough!"
The sound snapped the Emperor back to reality. He coughed loudly into his fist to hide his embarrassment, then nodded slowly, pretending he was merely deeply moved by the analysis.
"Pei Qing," he said, "if I wanted to permanently conquer and control Japan, how would you design the system?"
The question hit Pei Shiqing like a physical blow. He looked visibly shocked.
"Your Majesty."
He paused, carefully selecting his next words. He did not want to sound disrespectful.
"The Japanese people are crude. Their land is poor. They pose no threat to us. They lack the capacity to ever become a problem."
Pei Shiqing was not wrong. His assessment was entirely logical based on conventional wisdom. He had seen the place with his own eyes.
However, Li Shimin possessed knowledge from the future. His brain had been rewired by historical spoilers. He looked at the map differently now.
Neutralizing the Japanese threat was easy on paper. Build a huge navy. Blockade their ports. Cut off all maritime trade. Keep their population isolated and ignorant. Then secretly funnel money and weapons to rival clans. Let them butcher each other in endless civil wars. That strategy would guarantee peace on the eastern border for centuries.
But Li Shimin understood the true value of the ocean now. He knew exactly what that long chain of islands represented.
If the Tang Empire could eventually conquer those islands, it could build forward naval bases and turn the entire East China Sea into an inland lake. It would be like the Mediterranean Sea for the Roman Empire. They could stop any invasion hundreds of miles before it ever reached the mainland.
Furthermore, Li Shimin knew a secret.
Those islands were sitting on literal mountains of silver. At peak production, they could supply 30 percent of the world's silver. Their agricultural output was terrible, but their mineral wealth was staggering. Factoring in their strategic geographic location, the islands were a priceless prize.
Li Shimin had no idea whether Liu Rengui would actually manage to land troops on those beaches during the Zhenguan era. But a 100-year plan had to start somewhere.
Today seemed like a great day to start.
Pei Shiqing stood without speaking. He felt his blunt dismissal might have offended the Emperor. He opened his mouth to offer a more diplomatic answer.
Then he looked up.
The Emperor had turned around. Li Shimin stood with his hands clasped behind his back.
It was at that exact moment that Pei Shiqing finally noticed the new decor in the room.
His eyes locked onto a vast map hanging on the right wall. It consumed his entire field of vision. He immediately spotted the characters for Chang'an marked in the center.
What kind of map is this?
Pei Shiqing struggled to process the image. He had spent months on terrifying ocean voyages. He had drawn crude coastal charts by candlelight while his ship pitched in the waves. He knew what a coastline looked like.
He stared at the right side of the canvas.
The outline of the Liaodong Peninsula and the surrounding sea was flawless. It matched his memory perfectly.
If this map is real, it is the most terrifying document in the world.
Li Shimin spoke, his voice low and haunting.
"Pei Qing. Do you know that the oceans cover 70 percent of this world? Do you realize that if our descendants wish to survive, they must first master the sea?"
He took a step forward.
"Do you know that we live on a floating globe? Do you understand that foreign threats might one day descend upon this earth from the stars themselves?"
He turned his head. His eyes locked onto the diplomat.
"Do you know that if we truly want the 4 corners of the earth to submit, building a navy is our only option?"
The low voice slowly built into a passionate crescendo. The Emperor's gaze burned with intensity. The Emperor was clearly having a mental breakdown.
A thin line of sweat ran down the back of Pei Shiqing's neck. His logical brain screamed at him to run out the door and fetch the imperial doctors.
But his emotional instincts held him in place.
Li Shimin was a brilliant ruler. He never spoke nonsense without a reason.
Pei Shiqing swallowed hard and managed to force out a single sentence.
"Your Majesty. Do you have proof of these claims?"
Li Shimin pointed at a wooden chair.
"Sit, Pei Qing. This is going to be a very long story."
---
While the Emperor was delivering a private masterclass on global geography in Ganlu Hall, a different kind of struggle was unfolding across the city.
Inside the Directorate of Works, Yan Lide was covered head to toe in gray dust. He stood over a cracked block of cement resting on the ground, arms crossed, staring at it like it had personally insulted his ancestors.
"Does the difference between volcanic ash and industrial slag really change the outcome this much?" he muttered.
A man standing beside him tilted his head.
"What in the world is volcanic ash?"
It was the Vice Minister of the Directorate. He and Yan Lide went way back. Last year, the two of them had held the exact same rank. Then Yan Lide pitched a few ideas to the Emperor, Li Shimin loved them, and suddenly Yan Lide was the one sitting in the Director's chair.
The promotion never went to his head. Every time he started some insane new project, he dragged his old friends along for the ride. Nobody in the Directorate complained. The food was good, the hours were honest, and working under a boss who actually worked alongside you was worth more than any fancy title.
The Vice Minister leaned in.
"Well? What is it?"
Yan Lide waved a dusty hand. "It is ash. From a volcano."
The answer did absolutely nothing. A small crowd had begun to form around them. Master carpenters, stonemasons, and junior artisans had all stopped working to eavesdrop. The Director kept throwing around the word cement like it meant something, and every one of them wanted the secret recipe.
"Right. And a volcano is?" the Vice Minister asked.
Yan Lide paused.
Truthfully, he had no idea. The future texts mentioned volcanos, but they never bothered to provide a map. For all he knew, a volcano was some kind of very angry mountain that occasionally spat fire.
He clapped his hands together loudly and changed the subject.
"All right, enough standing around. This batch is a failure. Clear it out. We mix the clay, the slag, and the limestone again, and this time we get the ratio right!"
The artisans scattered, grumbling among themselves. The Vice Minister stayed behind.
Yan Lide bent down and picked up a heavy iron crowbar. He raised it over his shoulder and brought it down hard against the cracked cement block. He wanted to see how deep the fractures ran.
The iron bar slammed into the stone. A shockwave shot straight back up the shaft and into his palms. He dropped the bar with a sharp hiss, shaking his stinging hands.
"Son of a—" He caught himself. "That hurt."
He stared down at the hard gray rock. Slowly, a grin spread across his face.
He finally understood a strange phrase the future texts kept using. They called cement a black technology.
A metal bar bounced off the thing. His hands were still buzzing. If that was not black technology, he did not know what was.
The Vice Minister walked over, picked up the fallen crowbar, and jammed the flat end into one of the cracks. He leaned his weight into it, prying the block apart so Yan Lide could inspect the inside.
Yan Lide gave him a grateful nod. He crouched down and ran his fingers along the rough internal texture of the dried cement. His brow furrowed.
The recipe itself was not the problem. Chang'an had mountains of clay, limestone, and iron slag. Between the Director, the Vice Minister, and every half-decent brain in the Directorate, they had already worked out a mixing ratio that produced beautiful wet cement. The mud looked perfect when it went into the mold.
The nightmare started during the drying phase. Every single time the block cured, deep cracks spidered through it. It was driving Yan Lide up the wall.
The Vice Minister leaned on the crowbar. He wiped sweat from his forehead with the back of his wrist and studied the crumbling rock. Then he glanced at his friend's face and offered a completely casual suggestion.
"You know, maybe the mud is fine. Maybe it is just missing something inside. Like wooden rafters, or some kind of support beam."
Yan Lide froze.
He turned his head slowly, staring at the Vice Minister like the man had just recited a poem from the future.
"...Say that again."