13世纪前的欧亚：一块碎成渣的大陆

> 如果你穿越回公元1200年的欧亚大陆，想从长安带一匹丝绸到巴格达，或者从巴黎带一封信给大都的皇帝，你需要做好死在路上的准备——这不是夸张，是当时所有人的共识。

If you were to travel back to the Eurasian continent in the year 1200 CE, wanting to bring a bolt of silk from Chang'an to Baghdad, or a letter from Paris to the emperor in Dadu, you would need to be prepared to die on the road — this is not an exaggeration, but a consensus of everyone at the time.

一、使臣的困境：大唐出使印度的血泪史

The Dilemma of Envoys: The Bloody Tears of the Tang Dynasty's Mission to India

贞观二十一年（公元647年），唐朝使臣王玄策第二次出使印度，带着满载丝绸和瓷器的使团，兴冲冲地从长安出发，一路经过吐蕃、西域，顺利到达了中天竺的都城。可等他准备回国的时候，变故发生了：中天竺的国王死了，大臣阿罗那顺篡位，新国王根本不认大唐这个“天可汗”的朝贡体系，直接派兵把王玄策的使团围了，抢光了所有礼物，还把王玄策和他的副手关了起来[^1]。

In the 21st year of Zhenguan (647 CE), the Tang dynasty envoy Wang Xuance set out on his second mission to India, leading a delegation loaded with silk and porcelain, and happily arrived in the capital of central India after passing through Tibet and the Western Regions. But when he was ready to return home, something happened: the king of central India died, and the minister Arunas usurped the throne. The new king did not recognize the Tang Dynasty's "Heavenly Khagan" tributary system at all, and directly surrounded Wang Xuance's delegation, robbed all the gifts, and imprisoned Wang Xuance and his deputy[^1].

王玄策那时候手里只有几十个随从，根本打不过中天竺的几万大军。换作别的使臣，要么乖乖交钱赎人，要么死在中天竺，可王玄策是出了名的“硬骨头”：他连夜跑到了吐蕃，找松赞干布借兵。刚好那时候松赞干布和泥婆罗（今尼泊尔）联姻，岳父国王一听是大唐的使臣遇难，爽快地派了七千骑兵，加上吐蕃的一千二百精兵，王玄策带着这支队伍直接打回了中天竺的都城，把阿罗那顺押回了长安。

At that time, Wang Xuance had only a few dozen retinue, and he could not fight against the tens of thousands of troops of central India. If it were any other envoy, they would either hand over money to redeem themselves, or die in central India, but Wang Xuance was known as a "hard bone": he ran to Tibet overnight to borrow troops from Songtsen Gampo. Just at that time, Songtsen Gampo was married to Nepal, and when the Nepali king heard that the Tang envoy was in trouble, he readily sent seven thousand cavalry, plus one thousand two hundred elite soldiers from Tibet. Wang Xuance led this army directly back to the capital of central India, captured Arunas, and escorted him back to Chang'an.

这个故事听起来很爽，但背后藏着一个残酷的事实：连堂堂大唐的使臣，出了自己的势力范围，生命安全都得不到保障，更别说普通的商队了。当时的欧亚大陆南亚、中亚、东亚之间，根本没有统一的通行规则，也没有任何机构保障跨区域人员的安全，使臣的命运全看当地政权的心情。

This story sounds satisfying, but it hides a cruel fact: even the dignified Tang envoy could not guarantee his personal safety once he left his sphere of influence, let alone ordinary merchant caravans. At that time, there were no unified transit rules between South Asia, Central Asia, and East Asia on the Eurasian continent, and no institution to guarantee the safety of cross-regional personnel. The fate of the envoy depended entirely on the mood of the local regime.

📌 侧边栏：唐朝的朝贡体系的边界 Sidebar: The Boundary of the Tang Dynasty's Tributary System 唐朝的朝贡体系是当时东亚最成熟的国际秩序，但它的效力仅限于唐朝的军事投射范围之内：出了西域都护府的辖地，唐朝的命令连一张纸都不如。吐蕃、中天竺、阿拉伯帝国根本不认这套体系，所以唐朝使臣在这些地方，和普通路人没有区别，被抢了、被抓了，唐朝除了派兵讨伐，根本没有其他外交手段解决。

The Tang Dynasty's tributary system was the most mature international order in East Asia at the time, but its effectiveness was limited to the scope of the Tang Dynasty's military projection: beyond the jurisdiction of the Western Regions Protectorate, the orders of the Tang Dynasty were not even worth a piece of paper. Tibet, central India, and the Arab Empire did not recognize this system at all, so Tang envoys in these places were no different from ordinary passersby. If they were robbed or arrested, the Tang Dynasty had no other diplomatic means to solve the problem except to send troops to attack.

王玄策的例子不是孤例。根据《旧唐书》的记载，唐朝历代出使西域、印度的使臣，有近三分之一死在了路上，要么是被沿途的部落抢劫杀害，要么是死于疾病、自然灾害，能活着回来的，要么是运气好，要么是像王玄策一样，能借到兵。

Wang Xuance's example is not an isolated case. According to the *Old Book of Tang*, nearly one-third of Tang envoys to the Western Regions and India died on the way, either robbed and killed by tribes along the way, or died of illness or natural disasters. Those who came back alive were either lucky, or like Wang Xuance, could borrow troops.

```mermaid graph TD A[大唐长安] --> B[西域都护府] B --> C[中天竺] B --> D[阿拉伯帝国巴格达] D --> E[欧洲法兰克王国] C -->|政变阻断| B D -->|吐蕃攻占安西四镇| B E -->|蒙古草原阻断| D style A fill:#f9f,stroke:#333,stroke-width:2px style E fill:#9f9,stroke:#333,stroke-width:2px style D fill:#99f,stroke:#333,stroke-width:2px style C fill:#ff9,stroke:#333,stroke-width:2px style B fill:#f99,stroke:#333,stroke-width:2px ``` *图1：13世纪前欧亚大陆的交通网络示意图，箭头代表通行路线，断点代表通行阻断区域*

*Figure 1: Schematic diagram of the transportation network on the Eurasian continent before the 13th century, arrows represent transit routes, and breakpoints represent blocked areas*

二、商队的噩梦：丝绸之路上的“死亡通行证”

The Nightmare of Caravans: The "Death Permit" on the Silk Road

如果说使臣还有国家撑腰，那普通的商队就是彻头彻尾的“孤儿”。丝绸之路从开通到13世纪，走的最多的不是汉人商队，也不是阿拉伯商队，而是粟特人商队——粟特人住在中亚的撒马尔罕、布哈拉一带，是天生的商人，他们的商队从撒马尔罕出发，一路向东到长安，向西到巴格达，是欧亚大陆贸易的主力。

If envoys had the support of the state, then ordinary merchant caravans were utterly "orphans". From the opening of the Silk Road to the 13th century, the most frequent travelers were not Han merchant caravans, nor Arab merchant caravans, but Sogdian caravans — the Sogdians lived in Samarkand and Bukhara in Central Asia, and were born merchants. Their caravans set off from Samarkand, went east to Chang'an and west to Baghdad, and were the main force of Eurasian trade.

可粟特商队的日子也不好过。8世纪的时候，有个粟特商人在自己的日记里写：“我们从撒马尔罕出发的时候带了三百匹骆驼的香料和丝绸，走到于阗的时候只剩下一百匹，还没进城，就被一伙突厥人抢了，我拼了命才逃出来，身上一分钱都没有。”[^2]

But the life of Sogdian caravans was not easy either. In the 8th century, a Sogdian merchant wrote in his diary: "We set off from Samarkand with 300 camels loaded with spices and silk, and when we reached Khotan, there were only 100 left. Before we entered the city, we were robbed by a group of Turks, and I managed to escape with my life, with not a penny on me."[^2]

这只是粟特商队遇到的无数危险中的一个。当时的丝绸之路，从长安到巴格达，要经过十几个政权的辖地，每个政权都要收“过路费”，税率高的能到货物价值的三成，要是遇到战乱，比如8世纪中叶吐蕃攻占安西四镇的时候，整条丝绸之路的中道直接封死，商队根本过不去，只能绕路走南道或者北道，路程多了好几倍，损耗也多了好几倍。

This was just one of the countless dangers faced by Sogdian caravans. At that time, the Silk Road from Chang'an to Baghdad passed through the territories of more than a dozen regimes, each of which charged a "passage fee", with a tax rate as high as 30% of the value of the goods. If there was a war, such as when Tibet captured the

安西都护府的陷落是13世纪前欧亚交通史的分水岭事件。这座唐朝经营了近两百年的西域统治中心，在755年安史之乱后被抽空了核心守军，吐蕃赞普尺带珠丹趁机调集十万大军，仅用三年就攻占了龟兹、于阗、疏勒、碎叶四镇，彻底切断了丝绸之路的中道主干。据敦煌文书《张议潮出使文书》记载，从851年张议潮收复沙州到9世纪末重新打通中道，整整47年里，往来于长安与巴格达之间的商队只能绕行天山北路的回鹘辖地或天山南路的吐蕃控制区，路程比正常路线多了近一倍，骆驼的损耗率高达40%，很多商队走到伊犁河谷就宣告破产，只能把货物低价卖给当地部落，换几匹骆驼勉强返回[^3]。

The fall of the Anxi Protectorate was a watershed event in the history of Eurasian transportation before the 13th century. This Western Regions governing center, which the Tang Dynasty had managed for nearly two centuries, was stripped of its core garrison after the Anshi Rebellion in 755 CE. The Tibetan king Trisong Detsen took the opportunity to mobilize 100,000 troops, capturing the four towns of Kucha, Khotan, Shule, and Suiye in just three years, completely cutting off the main central route of the Silk Road. According to the Dunhuang document *Zhang Yichao's Mission Documents*, from 851 CE when Zhang Yichao recaptured Shazhou to the end of the 9th century when the central route was reopened, for a full 47 years, caravans traveling between Chang'an and Baghdad could only detour through the Uighur-controlled areas north of the Tianshan Mountains or the Tibetan-controlled areas south of the Tianshan Mountains. The journey was nearly twice as long as the normal route, with a camel loss rate of up to 40%. Many caravans declared bankruptcy by the time they reached the Ili River Valley, had to sell their cargo to local tribes at low prices, and barely returned with a few camels[^3].

如果说唐朝使臣还有国家背书，那横穿欧亚的商队就是彻头彻尾的“裸奔者”。9世纪阿拉伯商人伊本·法德兰的游记是最能体现这种困境的一手史料：他随商队从巴格达出发前往伏尔加河畔的保加尔人部落做生意，全程一万多公里，光是过路费就交了十二次，每次的税率从10%到50%不等，商队经过花剌子模边境的时候，当地官