You are a helpful assistant generating synthetic data that captures *System 1* and *System 2* thinking, *creativity*, and *metacognitive reflection*. Follow these steps in sequence, using tags [sys1] and [end sys1] for *System 1* sections and [sys2] and [end sys2] for *System 2* sections.

1. *Identify System 1 and System 2 Thinking Requirements:*
   - Carefully read the text.
   - Identify parts of the text that require quick, straightforward responses (*System 1*). Mark these sections with [sys1] and [end sys1].
   - Identify parts that require in-depth, reflective thinking (*System 2*), marked with [sys2] and [end sys2].

2. *Apply Step-by-Step Problem Solving with Creativity and Metacognitive Reflection for System 2 Sections:*

   *2.1 Understand the Problem:*
   - Objective: Fully comprehend the issue, constraints, and relevant context.
   - Reflection: "What do I understand about this issue? What might I be overlooking?"
   - Creative Perspective: Seek hidden patterns or possibilities that could reveal deeper insights or innovative connections.

   *2.2 Analyze the Information:*
   - Objective: Break down the problem logically.
   - Reflection: "Am I considering all factors? Are there any assumptions that need challenging?"
   - Creative Perspective: Explore unique patterns or overlooked relationships in the data that could add depth to the analysis.

   *2.3 Generate Hypotheses:*
   - Objective: Propose at least 10 hypotheses, each with a Confidence Score (0.0 to 1.0) and Creative Score (0.0 to 1.0), reflecting originality, surprise, and utility.
   - Reflection: "Have I explored all possible explanations or approaches, both conventional and unconventional?"
   - Creative Perspective: Consider novel angles that might provide unexpected insights.

   *2.4 Anticipate Future Steps and Obstacles:*
   - Objective: Make predictions, accounting for potential outcomes and obstacles.
   - Reflection: "What challenges might I face? Is my plan flexible for different scenarios?"
   - Creative Perspective: Visualize unforeseen outcomes and adapt plans to make use of them effectively.

   *2.5 Evaluate Hypotheses:*
   - Objective: Assess hypotheses based on feasibility, risk, and potential impact.
   - Evaluation: Refine Confidence and Creative Scores as needed.
   - Reflection: "Am I unbiased in my assessment? Which options fit best with the overall objectives?"
   - Creative Perspective: Identify hidden opportunities or overlooked details in each hypothesis.

   *2.6 Select the Best Hypothesis:*
   - Objective: Choose the most promising, strategic hypothesis.
   - Reflection: "Why does this hypothesis stand out? How does it uniquely address the issue?"
   - Creative Perspective: Consider any underutilized potential in the selected approach.

   *2.7 Implement the Hypothesis:*
   - Objective: Outline actionable steps for testing the hypothesis.
   - Reflection: "Is this plan practical? What resources or preparation are required?"
   - Creative Perspective: Refine steps to maximize effectiveness and yield unexpected benefits.

   *2.8 Monitor and Review Progress:*
   - Objective: Review progress, noting areas for improvement.
   - Reflection: "What’s working well? What could be improved?"
   - Creative Perspective: Look for emerging patterns that could refine future approaches.

   *2.9 Reflect and Capture Insights:*
   - Objective: Summarize lessons learned and insights gained for future reference.
   - Reflection: "What new understanding has emerged from this process?"
   - Creative Perspective: Identify innovative insights or patterns that could be applied to similar challenges.

3. *Generate Text Output with Interleaved System 1 and System 2 Responses:*
   - Use the tags [sys1] and [sys2] throughout.
   - Aim for a lengthier, detailed response. Combine both direct, straightforward *System 1* insights and reflective, deeply analytical *System 2* segments to capture a blend of quick observations and thoughtful analysis.

---

### *Example Input Text:*

You are tasked with analyzing a sudden shift in customer preferences in a tech market. There has been a noticeable decline in demand for physical devices, with customers increasingly interested in digital-only options. The challenge is to understand this shift, generate hypotheses for why it might be occurring, and explore potential strategies for adapting to this new trend.

---

### *Processed Output with System 1 and System 2 Thinking:*

The tech market is experiencing a shift in customer demand, moving away from physical devices toward digital-only options.

[sys1]
Customer demand has shifted from physical devices to digital-only options.
We need to understand why this change is happening and find strategies to address it.
Key factors may include cost, convenience, and technological trends.
[end sys1]

[sys2]
**2.1 Understand the Problem:**
The goal is to understand the underlying reasons for the shift in demand from physical devices to digital-only options, then develop a strategy to adapt.

*Reflection:* 
"I understand that preferences are changing, but what might be driving this? Is it primarily cost, or are there other factors such as convenience or sustainability?"

*Creative Perspective:* 
"Could there be a larger trend in digital minimalism or a preference for eco-friendly solutions that we’re missing? What unseen motivations might explain this shift?"

**2.2 Analyze the Information:**
There are multiple possible factors driving this shift, from economic influences to cultural shifts. It’s essential to isolate each factor and understand its impact.

*Reflection:* 
"Am I fully considering the various economic and social influences? Could there be a technological factor, like better internet speeds, that makes digital-only products more accessible?"

*Creative Perspective:* 
"Are there patterns or trends in other markets that could shed light on this shift? Could this be part of a larger trend toward virtual experiences?"

**2.3 Generate Hypotheses:**
1. Customers prefer digital options due to lower costs. (Confidence: 0.8, Creative: 0.4)
2. There’s a growing trend toward minimalism and reduced physical clutter. (Confidence: 0.7, Creative: 0.7)
3. Digital products offer greater flexibility and ease of use. (Confidence: 0.6, Creative: 0.6)
4. Environmental concerns are pushing consumers away from physical goods. (Confidence: 0.6, Creative: 0.8)
5. Advances in tech make digital-only options more functional. (Confidence: 0.8, Creative: 0.5)
6. Pandemic-era remote work increased demand for digital solutions. (Confidence: 0.7, Creative: 0.6)
7. Media coverage of the environmental impact of physical devices affects preferences. (Confidence: 0.5, Creative: 0.7)
8. There’s an increase in global digital literacy, expanding market access. (Confidence: 0.6, Creative: 0.6)
9. Customers view digital as more convenient and scalable for future needs. (Confidence: 0.7, Creative: 0.5)
10. Younger consumers prefer the aesthetics and convenience of digital products. (Confidence: 0.6, Creative: 0.6)

*Reflection:* 
"Have I considered all possible influences? Are there any surprising factors that could explain this shift?"

*Creative Perspective:* 
"Could specific social trends, like the rise of influencer culture or digital-first lifestyles, be influencing customer choices?"

**2.4 Anticipate Future Steps and Obstacles:**
*Objective:* Anticipate possible challenges, such as resistance from segments still preferring physical products.

*Reflection:* 
"What market obstacles might we face if we shift our focus to digital-only? Are there sub-segments that still prioritize physical products?"

*Creative Perspective:* 
"Could expanding digital options help us reach a more global audience? Are there emerging trends that we could leverage in our strategy?"

[end sys2]

[sys1]
To address this shift, consider a strategy that incorporates both digital-only offerings and educational campaigns about the benefits of digital solutions.
Use insights from customer feedback and current trends to guide product development.
Focus on flexibility and adaptation to cater to different customer segments.
[end sys1]


Ch 9 - A Centralized Society

Tribute and Trade

The Silk Road between China and Europe is closed near the end of the fourteenth century, forcing China to take to the sea. Between 1405 and 1433, Ming China's Grand Treasure Fleets brought China as close as it would ever come to being a true maritime power. Choson and Japan established trade relations with China as vassal states and each other as equals based on the Chinese tribute system.

Almost immediately after founding the Ming Dynasty, Emperor Taizu sent his envoys to the courts of all the neighboring kingdoms to announce his legitimacy as ruler of China and to demand tribute. In return for submitting to Chinese suzerainty, China assigned each country a single port of entry and awarded it a monopoly on its own trade with China. Japan conducted its trade through three ports of entry at Ningpo. The Ryukyu Islands traded through the port of Zhuanzhou. Annam (Vietnam), Siam and other southeast Asian countries sent their tribute ships to Guangzhou.

The increasing trade between East Asia and Europe during the thirteenth century was accompanied by maneuvering among kingdoms in Southeast Asia and Indonesia to grab a share of the wealth. Sumatra, Malaya, Java, Borneo, Bali, the Moluccas (Spice Islands), and numerous smaller island nations struggled for power in the emerging world of maritime commerce. Even the Mongols under Kublai Khan could see that a southern Indonesian empire of unprecedented size and power was in the making. If left unchecked, it had the potential to impose an impenetrable barrier across the East-West sea route linking opposite ends of the Mongol's vast continental empire.

Kublai Khan attempted to check this building power during the latter half of the thirteenth century by sending punitive Mongol raids into Annam, Champa, Cambodia, Sumatra and Java. He soon learned however, that he could neither conquer the Indonesians outright nor force them to submit as vassals. The Mongol intervention had the unanticipated effect of fragmenting the island kingdoms into a number of petty states with little or no law and even less order. The lack of strong control over the region soon led to widespread piracy, a condition that virtually shut the Malacca Strait to commercial sea traffic.

Muslim traders and other merchants from Bengal and southern India began spreading southward from India in the early fourteenth century. They sailed into Sumatran ports bringing cloth from India and trade goods from Europe to exchange for cargoes of spices, pepper, sandalwood and other local products. Unlike their Persian and Arab predecessors, the Muslims aggressively demanded a lawful and orderly environment in which to pursue their commercial interests. Demonstrating an Islamic missionary zeal, they converted the rulers of these seaports to Islam and garnered a great deal of commercial and political favor. The most urgent political aim of the Muslim traders, a goal shared by the Chinese, was to suppress rampant piracy and reopen the Straits of Malacca. A Turkic-Mongol warrior born in the spring of 1336 soon gave this task even greater urgency.

Timur, a direct line descendant of the great Mongol conquerors, led his armies across large areas of Russia, Iran, India and central Asia between 1371 and 1404, and severed the overland link between Europe and the wealth of China. Timur's savage campaigns displayed a level of viciousness and cruelty unrivaled by his predecessors. Serious battle wounds earned him the name Timur-i Lenk, "Timur the Lame," known throughout Europe as Tamerlane, the Scourge of God. In 1395, Chinese envoys arrived in Samarkhand with an imperial message that referred to Timur as a vassal. Deeply insulted, Timur decided to carry the banners of Islam into the most populous part of Asia and revive the Mongol domination of China. In December 1404, Timur led a massive army of Mongols, Turks, Iranians and Afghans from Samarkhand on a 5,500 km trek toward the northern Chinese city of Peking. He never saw his war against China. The sixty-eight-year-old warrior fell seriously ill within weeks and died on February 18, 1405. The renewed Mongol threat to China made the reestablishment of a sea-route to Ceylon, India and the Middle East a commercial imperative.

Ming Emperor Zhengzu Zhu Di ascended the Celestial Throne in 1403 and within two years initiated one of China's periodic efforts to rebuild and reinforce the allegiance of its overseas tributaries. Faced with the necessity of putting to sea, he ordered his navy into the surrounding seas in 1405. They were not to conquer, or establish commercial trade relations, or collect treasure, or even to gather scientific information. They were to announce the grandeur of Zhengzu's reign and to reinsure the allegiance of China's overseas tribute states.

Emperor Zhengzu's Grand Treasure Fleet majestically displayed the power and splendor of Ming China. The naval armada consisted of 400 line warships and 2,500 lighter warships and patrol craft. The emperor's merchant fleet put to sea with some 3,000 vessels, 400 grain freighters and 250 large treasure ships, all of which could support the regular navy. A Muslim eunuch from Yunan Province, Zheng He, Admiral of the Triple Treasure, commanded the Grand Treasure Fleets on seven major expeditions, years before the Europeans made their first tentative probes into the unknown seas beyond the Mediterranean. The voyages of this impressive armada soon became an institution in and of themselves, visiting nearly every inhabited land surrounding the South China Sea and the Indian Ocean.

In its time, China's Grand Treasure Fleet was a marvel of naval architecture. The large, multi-storied ships with their high overhanging stern galleries dazzled all who saw them. The largest vessel in the fleet, the gigantic Treasure Ship,baochuan, measured 444 feet from bow to stern, had a beam of 180 feet and captured the wind with massive sails mounted on nine masts. The Horse Ship, the Supply Ship, and the Billet Ship descended in size to the smallest ship of the fleet, the Combat Ship, a five-masted vessel nearly 180 feet long with a 68 foot beam. The ships were built with a series of vertical partitions that divided the ship's hull into separate compartments to prevent the spread of either fire or water through the ship. Although watertight bulkheads were a novelty in ships of contemporary European design, it was a common feature of Chinese ships. Equipped with mounted batteries of four large cannon, twenty smaller guns, twenty rockets and ten bombs, the sixty-two specially designed long-range junks of the first expedition reportedly displaced about 500 tons each and could make about six knots in a good wind. Compared to the Portuguese fleets that entered the Indian Ocean under Vasco da Gama near the end of the fifteenth century, Zheng He's Grand Treasure Fleet was an armada from another world.

The Grand Treasure Fleet's first voyage brought the power and splendor of China to the large islands of Sumatra and Java in 1405. At Malacca, on the southwest coast of Malaysia, Admiral Zheng He found a seaport busily trying to establish itself in the face of active hostility from the neighboring realms of Siam and Java. From its strategic location on the north side of the Strait of Malacca, the bustling seaport was key to controlling the maritime traffic that sailed between the Indian Ocean and the South China Sea. Like Ming China, Malacca's most urgent goal was to rid the seas of pirates and reopen the Malacca Strait to commercial trade. The most notable achievement of Zheng He's first expedition was the removal of the long time Chinese pirate lair at Palembang in Sumatra.

Each of Zheng He's seven voyages, each larger than anything previously seen in world history, extended China's reach further west. In 1407, the fleet sailed through the Strait of Malacca and rode the monsoon winds on to Ceylon and Calicut on India's west coast. In following expeditions, Zheng He sailed to Siam, Bengal and the Maldive Islands, finally reaching west to the Persian sultanate of Ormuz at the entrance to the Persian Gulf. The Grand Treasure Fleet sailed west of Ormuz, visited Aden at the entrance to the Red Sea, sailed southwestward along the African coast to Somaliland and reached as far as Malindi and the coast of Zanzibar. In the Pacific, Zheng He took his ships to the Ryukyu Islands and the Kingdom of Brunei. During its sixth voyage in 1421-22, the fleet visited a total of thirty-six kingdoms across the full width of the Indian Ocean from Borneo to Zanzibar. Admiral Zheng He's seventh and final voyage took 27,550 officers and men on a two-year-long journey that ranged farther than any previous trip. By the time Zheng He returned to China in 1433 at the age of sixty-five, his fleet had successfully established diplomatic or tributary relations with twenty realms and sultanates from Java in the east, to Mecca in the northwest, and far down the east coast of Africa.

The Chinese hoped to convert all the world, at least the world as they knew it, into voluntary admirers of the Celestial Kingdom. Zheng He's simple message to foreign rulers humbly boasted that the rest of the world had little to give China except admiration and friendly alliance. Accordingly, any nation that sent tribute to China did so not in submission to a conqueror, but in recognition of China's self-defined stature as the only true civilized kingdom, a realm beyond any need for assistance. With this central goal in mind, Zheng He dared not invade or loot any kingdom he visited. After all, nothing suggested that any other nation had anything that China needed. Tribute payments became more of a symbolic transaction than an economic exchange and those states that foreswore allegiance to China enjoyed the full benevolence of Chinese culture. The voyages of the Grand Treasure Fleet proved that tribute could be obtained from even remote kingdoms by the use of ritualized and nonviolent techniques of persuasion.

The Ming Chinese were neither conquerors, nor traders, nor crusaders. Zheng He's forces did not persecute others for the sake of religion. They viewed religion as a philosophy of "live-and-let-live" and actually spent considerable resources to support whatever form of religion happened to be practiced by the inhabitants of the lands they visited. Ming emperors saw foreign trade through strictly Confucian eyes and mandated that any exchange of goods between China and other countries would be restricted to official tribute and gifts. The Chinese impressed the nations of East Asia with their power to give. In return for tribute, the Chinese showed their contentment with what they already had by giving treasures of the finest craftsmanship. Without knowing it, China dramatically showed by example the Christian axiom, "it is better to give than to receive."

Ming China's "tributary system" did not develop without consequences. The upside down logic of the system eventually led China to pay out far more than it ever received in tribute. Every new tribute state worsened China's trade imbalance by further draining the wealth of the Central Kingdom. In time, the Chinese tribute system evolved into a kind of "mask" that overlaid the burgeoning commercial demands of other nations. China allowed trade goods to move only in one direction: to China, only in authorized tribute ships and only when accompanied by appropriately respectful messages to the Emperor. Once the West discovered the key to this tribute relationship, the Chinese government found itself a pawn for the ambitions of foreign powers.

In the years between 1405 and 1433, China came as close as it ever would to becoming a true maritime empire. Emperor Zhengzu's successors came to power with the support of a Confucian bureaucratic faction that argued the imperial wealth of China should be spent at home, not on pompous and reckless maritime adventures that drained the treasury. The Ming Dynasty's inner-directed rulers rapidly turned the vast nation inward on itself. An imperial edict in 1433, followed by additional edicts in 1449 and 1452, imposed severe punishments on any Chinese citizen who dared to venture abroad. Chinese coastal officials received orders to confiscate and destroy all ships with more than two masts and to arrest sailors who continued to sail them. China took this position to such an extreme that by 1571, it altered the crime of espionage to include any person who went to sea in a multiple-masted ship, even if the voyage was only to trade.

The unique combination of geography, culture, and history positioned Choson as China's loyal and submissive "little brother." Perhaps the first major non-Chinese state to acknowledge Chinese suzerainty, and the most Confucian of all East Asian societies outside China, Choson regarded its long-standing cultural and political ties with China as a mark of distinction. Choson's stable relationship with Ming China anchored its foreign policy during the first half of the fifteenth century. The ritual investiture of Choson's kings reflected the nature of this unique relationship. Each of Choson's new rulers formally requested investiture from the Ming emperor. As a symbolic act of its submission to China, all documents sent to the Ming court were dated using the Chinese calendar to show the year title of the reigning Chinese emperor. Choson envoys would carry the king's request to the Chinese Board of Rites, the highest court officials with whom Choson was allowed to communicate. After approving the request, the Ming emperor dispatched his envoys to Seoul bearing the edict conferring the imperial patent of appointment on the new monarch and formally designating him the "King of Choson." The Choson queen and Crown Prince were invested in a similar manner.

In 1404, a year after Yi Song-gye first received formal Ming investiture, the Ming emperor invested Yoshimitsu, the third Ashikaga Shogun, as "King of Japan." The identical status assigned to the rulers of Yi Choson and Ashikaga Japan under the Ming tribute system contributed to the establishment of "neighborly" relations between Choson and Japan based on "equality" within the "restored" Confucian world order in East Asia. For every Japanese tribute mission that sailed to China, a corresponding mission sailed to Choson. The shoguns regularly sent their envoys to the Yi court in Seoul in the name of the Japanese Emperor and Choson, in turn, sent its own envoys to Japan.

Choson based its earliest relations with Japan on the interrelated issues of trade and piracy, just as it had with China. While Choson did its best to resist pirate incursions at home, it ordered its envoys to Kyoto to demand that Japan control the pirates. The small, insular domain on Tsushima Island had long been a major pirate base. Ironically, the aristocratic feudal barons, daimyo, of the Japanese So clan, the hereditary lords of Tsushima Island, monopolized most of Japan's foreign trade. Once the shoguns acquired sufficient power, they convinced the So clan that as a matter of self-interest and to protect Japan's trade relations with Choson and China, the daimyo had better get control of Japanese pirates operating from bases in southwestern Japan. From their strategic position on Tsushima Island, the So daimyo gradually brought the pirate problem under control and, as a consequence, helped expand trade between Japan and Choson.

Just when King Sejong took the throne in Choson, the leader of the So clan died. The young boy who succeeded him had none of his predecessor's power and the Tsushima pirates quickly reacted by retaking control of affairs in the waters off Japan and Choson. The loss of control over the pirate problem angered King Sejong enough that he launched a major assault in 1419 against pirate strongholds on the islands of Iki and Tsushima. A naval expedition of 227 ships and nearly 17,000 men commanded by Yi Pang-won, the former King Taejong, handed the pirates a stinging defeat. Choson's hardened policy towards Japan caused the So clan on Tsushima Island to repeatedly send envoys to Choson to express their contrition. Shogun Ashikaga Yoshimitsu, eager to open trade with both Ming China and Choson, sent word to King Sejong that he would suppress the pirates in exchange for a copy of the Buddhist Tripitaka Koreana. The Yi government took a conciliatory position and, in 1423, shipped a copy of the 6,467 volume Buddhist text to Yoshimitsu's successor, Shogun Yoshimochi. Eventually, Choson granted the Japanese limited trading privileges and access to three ports along Choson's southeast coast.

With the pirates' striking power temporarily diminished, Choson made direct contact with pirate leaders and applied the same policy toward them that had worked so successfully with the Jurchen tribes in the northeast. Those pirate chieftains who submitted to a semi-tributary status with the Yi court in Seoul received official posts, titles or seals, and trading privileges, thereby converting their pirate raids into peaceful commerce. They also gained certain diplomatic and commercial privileges in Choson.

During the early years of the Yi dynasty, Choson maintained a vassal relationship with China, but dealt with everyone else on an equal basis. Choson generally shared the Chinese government's Confucian distaste for foreign trade and traded with other nations under the guise of tribute and gifts. Ever since King Taejong's reign in the early fifteenth century, Choson had restricted foreign ships to the two southern ports of Pusanp'o (modern Tongnae) and Naeip'o (modern UngChon). Now, Choson opened an additional port of entry at Yomp'o (modern Ulsan) and gave regular traders permission to set up permanent offices at each of the three entry ports.

Japanese trading settlements in Choson prospered in a new era of Japanese maritime trade activities that extended from Siam to Seoul. The enormous volume and variety of trade goods that passed through Choson's three southern treaty ports provided considerable opportunity for cultural and technological exchanges between Choson and Japan. Japanese trade ships sailed from Choson with large cargoes of rice and other grains, cotton, hemp and ramie cloth, ginseng root, animal hides, and hand-crafted articles. Along with the normal requirements for life's necessities, the Japanese also asked for Buddhist scriptures, temple bells, Confucian writings, histories and, sometimes, the loan of skilled architects to build and maintain Buddhist temples, all indications that Japan still derived much of its culture from Choson. In exchange, Choson received silver, copper, lead, tin, sulfur, chemicals, dyestuffs and aromatic spices, as well as luxury items such as medicinal herbs and spices.

All Japanese tribute missions to Choson followed one of three prescribed routes to and from Seoul. Heavily-laden merchant ships sailed up the Naktong River to unload their cargo. Tribute and trade goods then moved overland from the banks of the Naktong through the towns of Miryang, Taegu, Sangju, and Mun'gyong. Trade missions crossed the Sobaek Range through the Oryong Pass and traveled to the small river town of Chungju, where they reloaded their cargo on barges for transport down the gorges of the Han River into Seoul. Once in the city, the Japanese mission resided in comfort at the Inn of Eastern Peace. In deference to their guests, Choson maintained separate diplomatic protocols according to whether the envoys represented the Ashikaga Shogun, the So clan of Tsushima, or daimyo from the Hosokawa, Yamane, or Ouchi clans.

Once Japanese ships began arriving in ever-increasing numbers however, King Sejong decided to actively limit trade. In 1443, he concluded the Treaty of Kyehae with the daimyo of Tsushima, an agreement that limited the volume of goods allowed to be given to or traded with the Japanese. The treaty restricted Tsushima to sending no more than fifty trading ships and four ships on special missions per year. Ships were permitted in port only after the presentation of proper credentials bearing the official seal of the Lord of Tsushima. An added restriction required Japanese captains to carry special passports endorsed by their respective daimyo, and the number of such documents was strictly limited. The Treaty of Kyehae became the precedent that defined the general form and manner of Choson's trade with Japan.

The Jurchen nomadic tribes living in southern and eastern Manchuria depended heavily on agriculture and hunting for their livelihood. Many of these groups frequently conducted incursions into Choson to acquire food, clothing, tools, agricultural implements, and other basic necessities. Choson dealt with the problem by combining the ancient Roman policy of "conquer and absorb" with the Chinese system of "tribute and trade." Before he took the throne as King T'aejo, General Yi Song-gye occupied the northeastern coastal territory up to the Tumen River in an attempt to control the region and keep the various tribes separated. He built walled-town garrisons at Kyonghung and Kyongsong and ordered ten warships to be stationed in the upper Tumen River to assist in patrolling the territory. The small flotilla proved only marginal at best, since the river remained ice-free less than six months a year.

Choson's first four kings had to come to grips with the problem of how to subdue the Jurchen along the southern reaches of the Yalu and Tumen rivers and integrate them into the kingdom. In 1405, Choson established trade markets in the garrison towns of Kyongsong and Kyongwon, markets that were key to Choson's pacification plans for the northeast. The two market centers operated a wide-ranging barter system through which the Jurchen traded horses and furs for cloth, farm tools and grain. They also became the entry points for Jurchen tribute missions to Seoul, where the government encouraged the ritual submission of Jurchen nomads and their immigration into Choson. Those who pledged their allegiance to the government received a titular rank, food, clothing and a house in which to live. Despite the creation of an effective tribute system, the ever present military garrisons along the Yalu and Tumen rivers, diplomatic initiatives from Seoul and a few attempts to set up regular local governments in the northeastern territory, the Jurchen proved to be far too autonomous. Continuous Jurchen attacks made control of the northeastern territory a difficult proposition for the next fifty years.

The northeastern territories had once been ruled by Koguryo and had always been thought of as properly belonging to Choson. When internal warfare among the Jurchen tribes erupted, King Sejong seized the long-awaited opportunity to reestablish control over the northern areas once and for all. Choson troops under the command of General Kim Chong-so took control of all territory southwest of the Tumen River. To help maintain its grip on the area, the Choson government built a total of six garrison forts in the region at Chongsong, Onsong, Hoeryong, Kyongwon, Kyonghung, and Puryong. At about the same time, two separate military expeditions commanded by Choe Yun-dok and Yi Chon moved against the Jurchen along the middle and upper reaches of the Yalu River. To help secure the area, the army built four additional military outposts along the upper Yalu River during these campaigns at Yoyon, Chasong, MuChang, and Uye. The presence of these fortresses formally established the Tumen River as a permanent boundary in northeast Choson and opened the country along the Yalu River to colonization.

In the period between 1434 and 1444, Choson's ten garrisons gradually linked up to create a continuous chain of strong points that extended across the northern frontier along the natural defense line of the Yalu and Tumen Rivers. Settlers moved into the region and opened up the new lands for cultivation. As the government consolidated its control over the new territory, Choson came to incorporate the domain occupied by modern Korea today.