Unearthing Ancient Paths: How We’re Digitally Rebuilding the Sino-Korean Tribute Routes with GIS!

Hey everyone! Ever wondered how people in the olden days managed those epic journeys across vast lands? I’m talking about routes that weren’t just about getting from A to B, but were lifelines of culture, trade, and diplomacy. Today, I want to chat about something super fascinating I’ve been involved with: using some nifty digital tools, specifically Geographic Information Systems (GIS), to bring these ancient pathways back to life, focusing on the incredible Sino-Korean Tribute Routes from the Qing Dynasty (that’s 1616–1912, for us history buffs!).

So, What’s the Big Deal with Cultural Routes?

You know, since the 1980s, we’ve started to really appreciate these “cultural routes” as important heritage. Think of the famous Routes of Santiago de Compostela – that’s a prime example! UNESCO officially coined the term “Heritage Routes” or “Cultural Routes” back in 1994. They’re not just roads; they’re about exchanges, multi-dimensional dialogue across countries or regions, and they show how movement, people, and ideas interacted over space and time. The International Council on Monuments and Sites (ICOMOS) even has a whole charter for them, defining a cultural route as a dynamic mix of three things:

• The route itself, serving a specific purpose.
• Tangible stuff along it (like buildings or landmarks) that prove it existed.
• Intangible vibes – the stories, the cultural exchange, the memories.

Now, the tricky part is that traditional ways of documenting these routes, like old photos or hand-drawn maps, often fall short. These routes can be huge, complex, and sometimes, parts of them are damaged or have vanished entirely. This is especially true for “intangible” routes, like the Silk Road, which might not have a clear, paved path you can still walk on today. They might cross oceans, deserts, or dense forests, making them super hard to trace accurately.

Our Star: The Sino-Korean Tribute Routes

This is where our project comes in! We’re looking at the Sino-Korean Tribute Routes. For centuries, during China’s feudal dynasties, it was a major power in East Asia, and neighboring countries like Korea were part of a tributary system. Korea, in fact, was one of the most prominent vassal states, sending thousands of tribute missions to China. These envoys travelled from Seoul to various Chinese cities, and their paths are what we call the Sino-Korean Tribute Routes.

These routes weren’t static; they changed with dynasties and borders. But during the Qing Dynasty, they became pretty stable. One particularly important stretch was the Liaodong Eight Courier Stations Section. It wasn’t just a road; it was a bustling channel for political, economic, cultural, and even military exchanges. It perfectly fits the ICOMOS definition of a cultural route and is packed with historical value.

The problem? A lot of research relies on historical descriptions and photos, but there’s a gap in really interpreting and showing these routes as cultural heritage. That’s where GIS, specifically ArcGIS Pro, steps up to the plate!

Our goal is to digitally reconstruct these deteriorated and intangible routes. We’re focusing on a 210 km segment of the Liaodong Eight Courier Stations Section, from Jiuliancheng Courier Station to Liaoyang City. It’s like digital archaeology, but instead of digging, we’re using data!

Getting Our Hands Dirty: The Data Hunt

To rebuild these routes, we couldn’t just guess. We needed solid information. So, we dived into a multi-source data pool:

1. Historical Accounts: These are pure gold! We used:
   • The Yanxing Records: Diaries from Korean envoys themselves! They detailed routes, events, the environment, and personal observations. Imagine reading an envoy’s entry: “On December 7th, we traversed the Jinshi Mountain and Xichuan River, arriving at Tangshancheng Courier Station.” So cool!
   • Local Chronicles: Chinese local records documenting geography, city planning, and landmarks. For example, one might note: “Tongyuan Courier Station is situated 100 lis [~50 km] northwest of Fenghuangcheng City.”
   • Official Historical Records: From both the Qing Dynasty in China and the Joseon Dynasty in Korea. These big-deal chronicles documented important national events, including these diplomatic tribute missions.

   Sometimes these accounts conflicted, especially since envoys weren’t always familiar with Chinese place names. In such cases, we leaned on the more authoritative official records and local chronicles.

2. Historical Images: We’re talking drawings and maps. Some drawings were even made by the envoys, showing infrastructure, cultural activities, and the natural environment. Old maps, while not having precise GPS coordinates, gave us approximate locations of cities, mountains, and rivers, confirming their existence and spatial relationships.
3. Field Surveys: This is where we put boots on the ground! Historical records gave us relative positions, but we needed exact geographical coordinates. So, we went out to verify the locations of elements identified in the texts and images. We collected GPS data for key stations and took photos of any remaining heritage fabric and environmental features (like rivers and mountains) that might have influenced the original routes. This helped clear up ambiguities and gave us solid data for our digital reconstruction.
4. Online Geospatial and Environmental Data: Even with all the above, the exact paths between stations were still a bit fuzzy. So, we turned to modern online sources for data on geographical and environmental factors – things like hydrology (rivers, streams), slope (how steep the land is), terrain undulation (how bumpy it is), land cover (forests, fields), precipitation, and temperature. This data would help us simulate the most likely paths the envoys took.

Zooming in on the Liaodong Eight Courier Stations Section

The Liaodong region, where this section lies, has seen a lot of urbanisation, meaning parts of the route and its heritage elements are damaged or gone. Our first big task was to identify all the physical bits and pieces envoys would have passed. After sifting through historical accounts and images (and over 600 academic studies!), we pinpointed 54 “stations” along this section. These included eight main courier stations (official spots for messages, lodging, and horse-exchange) and 46 “normal stations” like towns, villages, and bridges.

Our field surveys confirmed the existence and precise locations of these 54 stations. For those with no physical evidence left, we cross-referenced historical accounts with local oral histories and topographic features. This gave us a reliable geospatial dataset, which we then visualized in GIS, giving us a rough outline of the route.

Now, here’s a key thing: there’s no evidence that special roads were built just for these tribute missions. So, we consider them intangible cultural routes. Just connecting the 54 stations with straight lines wouldn’t be accurate enough. We needed to consider what would have influenced their travel choices back then.

The Lay of the Land: Environmental Challenges

The Liaodong region is no walk in the park! It borders Korea across the Yalu River and has the Changbai Mountains running through it. This means varied elevations, with rivers flowing east into the Yalu and west into the Taizi River. The most efficient route would naturally follow these river valleys. The courier stations were cleverly built to take advantage of these natural conditions.

But envoys still had to cross multiple mountain ranges and rivers – big challenges! Add to that the climate: cold winters (around -10°C) meant frozen rivers and mountain roads. Summers brought heavy rain (over 800mm annually in many areas), leading to swollen rivers, floods, and travel disruptions. One envoy in 1564 was delayed 18 days due to flooding! Plus, all that rain meant dense forests, making travel on foot or horseback even tougher and riskier. So, envoys would have tried to find paths with milder temperatures, avoiding heavy rain areas and dense forests as much as possible.

To accurately simulate their likely routes, we had to consider the combined influence of:

• Hydrology (rivers, streams)
• Slope (steepness)
• Terrain undulation (bumpiness)
• Land cover (forests, cropland, etc.)
• Precipitation
• Temperature

Since we don’t have precise historical geographical data from the Qing Dynasty (imagine!), we used the earliest accessible modern datasets as proxies (like precipitation/temperature from 1950, land cover from 1990). We know this isn’t perfect, as landscapes change, but it’s the best approximation we can get, assuming major patterns have remained relatively stable.

Let’s Get Digital: GIS to the Rescue!

Alright, now for the really cool part: using ArcGIS Pro to reconstruct the path. This involved three main stages:

Stage 1: Creating Single-Factor Cost Rasters

Think of a “cost raster” as a map where every tiny square (pixel) has a value representing how “costly” or difficult it is to travel across it. We made one for each of our six environmental factors:

• Hydrology: Using waterway data (canals, rivers, drains, streams), we assigned different cost values based on how hard it would be for an envoy to cross. A big river? High cost! A small stream? Lower cost.
• Slope: Using Digital Elevation Model (DEM) data, we calculated the steepness of the terrain. Steeper slopes = higher cost to walk. We used a method called Natural Breaks Classification (NBC) to group slopes into 10 cost levels.
• Terrain Undulation: Also from DEM data, this measures how much the elevation varies over a broader area. A complex, bumpy landscape means more difficult route planning and higher walking costs. Again, 10 cost levels using NBC.
• Precipitation: Using data from 1950, areas with higher rainfall were given higher cost values (remember those floods!). 10 cost levels.
• Temperature: Also from 1950 data. We assumed envoys would prefer milder temperatures, so extreme cold or heat (though November data was used, focusing on avoiding cold) would mean higher costs. 10 cost levels.
• Land Cover: Using 1990 data, different land types (forest, cropland, shrub, grassland, water, etc.) were assigned costs based on accessibility. Dense forest? High cost. Open grassland? Lower cost.

For each of these, the GIS software generated a map where darker colours usually meant higher “travel cost.”

Stage 2: Mashing It All Together – Cost-Weighted Rasters

Now we had six separate “cost” maps. But how do these factors combine? We used a “Weighted Sum” tool in ArcGIS Pro to overlay them. This is where it gets interesting because we had to decide how much importance (or “weight”) to give each factor. We tried three different methods:

1. Reference-Based Evaluation: This is a bit subjective, relying on academic literature and expert knowledge. Historically, travel was by foot, horseback, or carriage, so terrain (slope and undulation) was super important and changes less over time. So, we gave slope and terrain undulation a higher weight (0.3 each), while land cover, temperature, precipitation, and hydrology got lower weights (0.1 each). Rivers, for instance, were generally crossable, so hydrology got a lower weight.
2. Entropy Method: This is an objective, data-driven method. It looks at how much each factor’s cost data varies. If a factor has a lot of variability, it’s considered more influential and gets a higher weight. It’s all math, no opinions!
3. Principal Component Analysis (PCA): Another objective method. PCA is a smart algorithm that simplifies complex data by finding the main patterns (principal components). It figures out which factors contribute most to the overall “cost” and assigns weights accordingly.

Each of these methods gave us a final “combined cost raster” map, showing the overall difficulty of traversing any point in our study area.

Stage 3: Finding the Best Path – Least-Cost Path (LCP) Analysis

With our combined cost raster map ready, we used the Least-Cost Path (LCP) algorithm. This is a standard GIS tool that finds the optimal path between an origin and a destination by minimizing the total cumulative “cost” (difficulty) to travel. We had 54 stations, meaning 53 segments to connect. To do this efficiently for all segments, we used the ‘Model Builder’ tool in ArcGIS, which is like creating a mini-program to automate the process.

We ran this LCP analysis three times, once for each of the cost-weighted rasters we created (Reference, Entropy, and PCA). This gave us three slightly different potential routes for the Liaodong Eight Courier Stations Section.

Did It Work? Putting Our Reconstructed Route to the Test!

So, we had three routes. Which one was “best”? We did a sensitivity analysis. This basically checks how much the routes change if you tweak the weights of the factors. We looked at the cost distribution and length distribution for paths generated by each method. Turns out, all three methods produced paths that were pretty darn similar in terms of length and cost patterns! The JSD (Jensen-Shannon Divergence – a fancy math way to compare distributions) values were low, meaning the differences weren’t huge. This was great news – it meant our overall framework was robust and not overly sensitive to how we assigned weights.

However, when we looked at the total sum cost for each route, the one generated using the reference-based evaluation method (where we gave more weight to slope and terrain) had the lowest sum cost – almost 50% lower than the others! This suggested it was the most “efficient” route based on our historical understanding. So, we picked this one as our final reconstructed route for the Liaodong Eight Courier Stations Section.

To make it even clearer, we generated an elevation profile chart, showing the ups and downs the envoys would have faced along this reconstructed path. It really brings the journey to life!

But wait, there’s more! To further validate our route, we used Viewshed Analysis. Historical records mentioned five high-elevation sites (viewpoints like Dajinshan Mountain and Fenghuang Mountain) that envoys could see from the route. We checked if these viewpoints were visible from our digitally reconstructed route using GIS. And guess what? All five sites fell within the visibility range! This was a fantastic confirmation that our GIS-reconstructed path lined up with historical descriptions.

Not Perfect, But Pretty Darn Good! (And Why This Matters)

Now, no study is perfect, and we acknowledge some limitations. Historical information can be limited, and we might not have identified every single station. The modern environmental data we used is an approximation of Qing Dynasty conditions. And, of course, envoys over a thousand years likely took slightly varied paths.

Despite these, by confirming 54 stations and breaking the 210 km route into smaller, manageable segments (averaging less than 4 km), we reduced complexity and improved accuracy. We used the best available data and validated our results scientifically. The path we reconstructed isn’t meant to be the exact trajectory of every single mission, but it gives us incredible insight into the primary movement patterns.

So why is this GIS-based reconstruction method so exciting?

• It’s precise and has controlled error margins.
• It’s widely applicable to other cultural route projects.
• It’s relatively user-friendly, so heritage pros without deep GIS expertise can use it.

The reconstructed routes are a crucial foundation for so much more:

• Heritage Preservation e Tourism: We can identify areas for preservation and plan sustainable tourism that respects the heritage.
• UNESCO Nominations: This can help with nominations and refine conservation policies.
• Education e Museums: Imagine dynamic, interactive museum exhibits or educational programs using this data! Think 3D models, animations, VR, and AR experiences where you can virtually walk these ancient routes.
• Enhanced On-Site Experiences: Mobile apps could use these routes as interactive guides for visitors actually exploring the areas.

This approach really helps us overcome the limits of old-school presentation methods, especially for routes that are complex, damaged, or even intangible.

What’s Next on This Digital Adventure?

While GIS is amazing for reconstructing the path itself, cultural routes are more than just lines on a map. They’re about the tangible heritage (buildings, artifacts) and intangible heritage (stories, cultural practices) connected to them.

Our future work will focus on integrating these elements. We’re looking at using 3D laser scanning and photogrammetry to document and reconstruct tangible heritage along the routes. Then, using tools like Unreal Engine, we can create immersive historical scenes, complete with environmental landscapes, historical narratives, cultural activities, and even soundscapes! This will give a much richer, more holistic presentation of the Sino-Korean Tribute Routes.

We’ve already made good progress, and I’m excited to share more results in the coming years. It’s all about using these incredible digital technologies to better understand, preserve, and share our amazing global heritage. Pretty cool, huh?

Source: Springer Nature