网帖翻译

Yu-Hsing Chen
Because the Chinese dynasties had long moved away from Xi’An and for good reason.
Even the last great period of Xi’An (ChangAn) being the capital, the Tang era, we were already seeing why this was the case, although ChangAn was better known as the capital, most non-history buffs aren’t aware that during the actual glory years of the Tang the Emperors spent at least as much if not more time operating out of Luoyang.
There’s several obvious geographic reasons to this.

因为中国历代王朝早已远离西安，而且有充分的理由。
甚至在最后一个伟大的时期，西安(长安)作为都城的唐朝时期，我们已经看到了为什么会这样，尽管长安作为都城更为人所知，但大多数非历史爱好者并不知道，在唐朝的真正辉煌时期，皇帝们至少花了同样多的时间在洛阳。
这有几个明显的地理原因。

As one can see pretty clearly from google map, Xi’An sits in the middle of a large basin while LuoYang opens up into the vast open plans of the Huang-Huai (Yellow River and Huai River.)
This means that as an administrative center LuoYang simply makes much more sense as it gives much easier access to a much larger part of your economy when it’s mostly farming based.
So why was Xi’An so popular in the earlier dynasty then? the reason is security, it wasn’t an accident that the Qin won in the chaotic struggles of the Warring States, while some may point to the legalist reform the realities was that the other states more or less copied that (and some even preceded the Qin.) The different was that most of the other 7 were in the exposed plains while Qin was hiding safely in a basin. That’s why Qin basically never had an army run over them during the entire period while everyone else kept getting hit (and not just from the Qin.)

从地图上可以很清楚地看到，西安位于一个大盆地的中部，而洛阳则进入了黄淮(黄河和淮河)广阔的平原。这意味着作为一个行政中心，洛阳更有意义，因为当洛阳主要以农业为基础时，它更容易进入你的经济中更大的一部分。
那么，西安在中国早期为什么如此受欢迎呢?原因是为了安全。秦国在战国的混乱斗争中获胜并不是一个意外，虽然有些人可能会指出是法家改革，但现实是其他国家或多或少地复制了这一点(有些甚至先于秦国)。不同的是，其他7个国家的大部分都在裸露的平原上，而秦国则安全地躲在一个盆地里。这就是为什么秦国在整个时期基本上没有军队碾压他们，而其他人一直在被打(而且不仅仅是秦国的)。

So Xi’An ‘s logic is that “If things goes to hell, we’re in the safest spot!” and that’s why it’s popular because one forgets that in the early Han era they divided the country back up into fiefs and thus until the middle parts of the Western period was still facing civil war risks. ( Only the Yellow parts were directly under the emperor in Early Han.)
Once the Han removed all the fiefdoms , they ended up shifting their capital to LuoYang as well in the second period as it is simply a more logical administrative center.
The same goes for the Sui-Tang period, when Sui first came to be it had just recently unified the North and there was still a southern state. that’s why it also went with Xi’An. (which was their capital before unifying the North anyway.). The Tang fought an all out warring states like situation after the Sui collapsed and own in no small part due to them seizing Xi’An early. ( Partly because they were IN the basin to begin with. )
So why did they shift away from LuoYang? because of the Tang dynasty’s failures made Chinese rulers realize another critical problem. That if you put your capital in the middle of the country that can control most of the farmlands that’s all good, but the downside is that you would be far away from your armies AND you are not in a safe defensive region.

所以西安的逻辑是，“如果事情变得很糟糕，我们在最安全的地方!”这就是为什么它流行（成为首都）的原因——因为人们忘记了，在汉朝早期，他们把国家分成了封地，因此直到西汉时期的中期仍然面临着内战的风险。
汉初时，只有黄色区域直属于皇帝。一旦汉朝清除了所有的封地，他们最终在第二个时期将首都转移到洛阳，因为洛阳是一个更合理的行政中心。隋唐时期也是如此，当时隋朝刚刚统一了北方，还有一个南方国家。这就是为什么它也选择了西安。(反正在统一北方之前，这里是他们的首都。)
隋朝灭亡后，唐朝发动了一场像隋朝一样的战争，由于唐朝早早地占领了西安，唐朝占有了相当大的土地。(部分原因是他们一开始就在盆地里。)
那么，他们为什么要离开洛阳呢?因为唐朝的失败让中国统治者意识到另一个关键问题。如果你把首都放在可以控制大部分农田的国家中部，这很好，但缺点是，你会远离你的军队，你没有在一个安全的防御区域。

So places like Kaifeng and Beijing were the solution to needing both security and administrative efficiency. If you notice Beijing is ALSO one of the key entry point into the major plains. though not quite as ideal as Luoyang, the difference is that Beijing is also the FRONT LINE.
The solution that the Chinese rulers came up with to the Tang era problem was to make sure the armies was close to the capital and thus makes warlordism less likely to happen. but the only way to do that without a huge wasteful army would be to keep the capital close to the front line. and that’s exactly what the Song and Ming did (though the Ming originally started from Nanjing which is more of the logic of Xi’an’s safety + Luoyang’s access. but that was quickly proven to fail when again a rebellion took the capital. the Song choice of Kaifeng was before it didn’t hold Beijing.)

所以像开封和北京这样既需要安全又需要行政效率的地方就成了解决方案。如果你注意到北京也是进入大平原的关键入口之一。虽然不如洛阳理想，但不同的是北京也处于第一线。
中国统治者想出的解决唐朝问题的办法是确保军队靠近首都，从而减少军阀主义发生的可能性。但要做到这一点，又不浪费庞大的军队，唯一的办法就是让首都靠近前线。这正是宋朝和明朝所做的(尽管明朝最初是从南京开始的，这更多是出于西安的安全+洛阳的入口的逻辑。但很快就被证明失败了，一场叛乱再次占领了首都。宋朝选择开封是在北京还没有成为首都之前。)

The other big factor was the development of the Grand canal, access to the canal shortened the geographic boundary to the areas that is connected, however the natural geographic constraints still means some cities are easier to connect via the canal than others, of the major post Canal capitals in the north, the relative usefulness is basically Kaifeng > Beijing > Luoyang >>>>>>>>>>>>>>>>>>>>> Xi’An. as Xi’An proved to be impossible to connect by the canal as it’s simply much higher . Luoyang suffer this to some degree as well but they could get it close enough.
Kaifeng was technically the best as it is literally where the Yellow Rivers (they never really could solve the problem of the Yellow River, so essentially the connection south and north of the river were two separate system. ) intersected with the Canal. but the problem was that by the Ming / Qing it was too far from the front line (and also too flood prone.) and of course, Beijing was also reasonbly close to sea so it had the help of sea port as well.

另一个重要因素是大运河的发展，运河的存在缩短了连接地区的地理边界，然而自然地理的限制仍然意味着一些城市通过运河比其他城市更容易连接，在北方的主要可以连接运河 的首都中，相对有用的基本是开封>北京>洛阳>>西安。因为西安被证明是不可能通过运河连接的，因为它地势高得多。洛阳在某种程度上也遭受了同样的痛苦但他们离得更近一些。
从技术上讲，开封是最好的，因为它是黄河的所在地，与运河相交。但问题是，到了明/清时期，它离前线太远了(也太容易发生洪灾)，而显而易见的，北京相当靠近大海，所以它也有海港的帮助。

If you read the Tang era ‘s actual administration happenings in it’s good time you see why this was a problem, the main reason given for moving to Luoyang almost always came down to that anytime there was sub-par harvest in the basin around the capital made it difficult to sustain the extra court / administrative population. because getting supplies from the canal would still require ox carts pulling hundreds of KM from the Luoyang area where most of the supplies would be wasted.
The records of the Tang suggest that pre-Anshi rebellion period, here were the times when the Tang moved it’s entire court to Luoyang.
Taizhong period : 637 AD (12 months), 641 AD ( 8 months) 644 AD (3 months but the emperors then went on a expedition and only returned the next year.) Gaozhong period: 657 AD (12 months) 659 AD ( 3 years!) 665 AD ( 1 year) 671 AD (22 months) 674 AD ( 15 months) 679 AD ( 22 months ) 682 AD (20 months and he died there. )
Empress Wu : the 22 years after Gaozhong’s death LuoYang became the defecto capital and they very rarely went back to ChangAn.
Xuan Zhong: 717 AD (22 months ) 722 ( 13 months) 724 ( almost 3 years ! ) 731 ( 14 months ) 734 ( 22 months.)
And after that Anshi rebellion happened.
So if you look at this picture it’s pretty astonishing that our supposed last glorious period of Xi’An the Tang court decided to spent basically more than half of the time away from that city

如果你了解过唐朝时期的实际行政管理，你就会明白为什么这是一个问题，迁居洛阳的主要原因几乎都是由于首都周围流域的收成不佳，很难维持额外的朝廷/行政人口。因为从运河获取物资仍然需要牛车从洛阳地区运数百公里，而洛阳地区的大部分物资都被浪费了。
唐朝的记录表明，在安史之乱之前，唐朝把整个朝廷都迁到了洛阳。
太宗时期:公元637年(12个月)，公元641年(8个月)，公元644年(3个月，但皇帝随后出征，第二年才回来)。
高宗时期：公元657年(12个月)，659年(3年!)，665年(1年)，671年(22个月)，674年(15个月)，679年(22个月)，682年(20个月，他死在那里)。
武皇：高宗死后的22年，洛阳成为陪都，他们很少回长安。
玄宗：公元717年(22个月)，722年(13个月)，724年(将近3年!)，734年(22个月)。
在那之后,安史之乱爆发。
因此，如果你纵览整个图景，令人惊讶的是，我们认为的最后一段辉煌时期，唐朝廷决定把一半以上的时间花在远离那座城市的时间里。

Michael Moldenhauer

Interesting to point out that it seems that the city was named for this feature of being a secure spot: the name means “western security”: 西安 = 西 “west” + 安 “secure, peaceful, at ease, safe”. The last character shows up also in the (more modern?) coinage for the (at least Chinese) police: 公安 - “Public Security [Ministry]”.
有趣的是，这座城市的名字似乎就是因为它是一个安全的地方。这个名字的意思是：
“西安”=“西部”+“安全、和平，放松”。最后一个字也出现在警察术语里(至少在中国是这样)的新造词中:公安=“公共安全”。

Leonard Todd
Good analysis. I just want to add that Beijing was chosen as the capital first by northern nomadic tribes as it is right at the geographic middle between nomadic society and agriculture society.

分析得很好。我想补充的是，北京首先被北方游牧部落选择为首都，因为它正好处于游牧社会和农业社会的地理中间位置。

Thomas de La Marnierre (トマ・サレ)
Why was Chang’An ‘s name changed ? In modern Greece, the names of the cities had changed over time and they were restored to their antique version because it was more prestigious that way. How come this did not happen in China ?

长安的名字为什么要改?在现代希腊，城市的名字随着时间的推移而改变，但它们随后被恢复到古代版本，因为那更有声望。为什么这没有发生在中国?
原创翻译：龙腾网 https://www.ltaaa.cn 转载请注明出处

Helen Shi
The answer to your questions deserves a separate answer on its own, as the historical explanation is rather long. The “official” name change happened in Ming dynasty, year of 1369 AD, but the city and surrounding area had multiple name changes between Tang and Ming dynasty and thereafter. The reason for not switching back is complicated as the city had many names during various dynasties, you can’t just pick one over another without encountering some counter arguments, or being accused of favoring one part of history over another.
Also, for the name change to happen, it means that every level of Chinese government, from local to provincial (it’s the capital of Shaanxi Province) to federal/central has to agree, along with a wide support of local population, probably the most or entire province. Just too much manpower being spend on something that has more symbolic value than practicality, when the average people would rather see more pressing issues affecting their daily lives get resolved first.

你的问题的答案值得单独回答，因为历史的解释相当长。城市“正式”名称的改变发生在公元1369年的明朝，但城市及其周边地区在唐、明及以后有多次更名。不改回去的原因很复杂，因为这座城市在各个朝代都有很多名字，你不能只选一个而不遭遇反驳，或者被指责偏袒历史的一部分。
此外，更名意味着中国各级政府，从地方到省(陕西省省会)到联邦/中央政府，都必须同意，以及当地人口的广泛支持，可能是大部分或整个省份。只是把太多的人力花在象征价值大于实际价值的事情上，而普通人更希望看到影响他们日常生活的更紧迫的问题得到解决。

Xiao Zhang
This question makes me think of the Geographical Pivot of History and it can be answered better in terms of geopolitics. China, sicne ancient times, could be generally divided into two parts: Inland China and Outer Buffer Zones.
Inner China, may I “invent” this term, includes the North (painted red with different shades) and the South (painted green with different shades).
The North includes North China, Guanzhong (because it is located within four passes), and Central Plain (also called Central Kingdom)。
The South includes Sichuan (Upstream of Long River), Central China (Midstream of Long River), East China (Downstream of Long River), Southwest China, South China, and Southeast China.
Outer Buffer Zones include Northeast China (called Manchuria before 1949), Inner Mongolia, Xinjiang (called Western Region before Ming Dynasty), Tibet and Vietnam (totally out of control of China since 1000 years ago).

这个问题让我想到了历史的地理枢纽，从地缘政治的角度可以更好地回答这个问题。
中国，自古以来，可以分为两个部分:中国内陆和外部缓冲区。
中国内地包括北方和南方。
北方包括华北、关中(因为它位于四关之内)和中原(又称中央王国)。
南方包括四川(长江上游)、华中(长江中游)、华东(长江下游)、西南、华南和东南。
外部缓冲区包括中国东北(1949年以前叫满洲)、内蒙古、新疆(明朝以前叫西域)、西藏和越南(1000年前就完全不受中国控制了)。

As have repeated many times since ancient times, the rules of geopolitics of China can be summarized as below:
If you can control Inland China, you can control Outer Buffer Zones.
If you can control Sichuan, you can control the South.
If you can control the North, you can control Sichuan.
If you can control Central Plain, you can control the North.
We can find that, in this chain, Central Plain is of great importance in controling the whole country. In ancient times, Chinese even had a term to describe this, “chasing the deer in the Central Plain”. When the centralized government fell and a large-scale civil war began, warlords were competing for the crown in the Central Plain.

中国的地缘政治规律，自古以来就有过多次的重复，其总结如下:
如果你能控制中国内陆，你就能控制外部缓冲区。
如果你能控制四川，你就能控制南方。
如果能控制北方，就能控制四川。
如果你能控制中原，你就能控制北方。
我们可以发现，在这条链条中，中原对于控制整个国家是非常重要的。在古代，中国人甚至有一个词来形容这种现象，“逐鹿中原”——当中央政府倒台，一场大规模的内战开始时，中原地区的军阀争夺王权。

Zhou, Qin, Han, Sui, and Tang placed their capital in Chang’an (ancient name of Xi’an) and Xianyang (close to Chang’an), two cities in Guanzhong, becasue they conquered the Central Plain from their base in Guanzhong. The founders of these dynasties were military aristocrats, whose power, wealth and army were mainly concentrated in Guanzhong. As the center of Guanzhong, Chang’an was the natural choice for capital. But Luoyang, the center of Central Plain, was also the center of transportation and commerce in the whole country. To spread their influence to and maintain their control on Central Plain, the military aristocrats from the west moved their capital to Luoyang, or simply kept both Chang’an and Luoyang as their capitals. From Zhou Dynasty to Tang Dynasty, in most occasions, if you can control Guanzhong, you can control Central Plain.

周、秦、汉、隋、唐都把他们的首都放在长安（西安古称）和洛阳（靠近西安），位于关中的两座城市，因为他们可以立足关中占领整个中原。这些王朝的建立者都是军事贵族，他们的权力、财富和军队主要集中在关中。
作为关中的中心，长安是建都的自然选择。但洛阳，中原的中心，也是全国的交通和商业中心。西部的军事贵族为了扩大影响并保持对中原地区的控制，纷纷迁都洛阳，或者干脆将长安和洛阳都保留为都城。从周朝到唐朝，大多数时候，能控制关中，就能控制中原。
金朝和宋朝都在洛阳和开封(靠近洛阳)，这两个城市位于中原。这两个王朝的建立者都是从中原崛起的。

The Mongols and the Manchurians established their capital in Beijing because they wanted to keep a balance between controling the North and controling their home. If they established their capital in Chang’an, Luoyang, or even Nanjing, they would get big trouble when they wanted to retreat to their home. Because they might be surrounded by the flourishing rebels. The Ming Dynasty established Beijing as capital since the thrid Emperor, because his political and military base was in North China. The rulers of Yuan, Ming and Qing Dynasty spreaded their influence to Central Plain from North China, so they placed capital in Beijing.
The capital of China has always been in the North, but it follows a path from west to east and then from south to north. And this historic trend has been proven irresistable. When People Republic of China was founded in 1949, the base of the Communist Party was the North and Northeast China. If you want to choose a city as capital, Beijing must be the best choice. Northeast China was the only region in China that had been high industrialized in the 1940s, where lots of weapons could be manufactured to sustain the war.
In summary, the Central Plain is the key to unify whole China. When warlords and strongmen could use the resources of Guanzhong to control the Central Plain, the capital would be Chang’an (Xi’an); when they rose to power based on the resources of the Central Plain, the capital would be Luoyang or Kaifeng; when they could use the resources of Mongolia, Northeast China or North China to control the Central Plain, the capital would be Beijing.

蒙古人和满洲人在北京建立了他们的首都，因为他们想在控制北方和控制他们的家园之间保持平衡。如果他们在长安、洛阳、甚至南京建都，他们想退居他乡，就会遇到大麻烦。因为他们可能会被叛军包围。明朝从第三代皇帝起就定都北京，因为他的政治和军事基地都在中国北方。元、明、清三朝统治者将势力从华北扩展到中原，都城设在北京。
中国的首都一直在北方，但它走的是一条由西向东，再由南向北的道路。事实证明，这一历史趋势不可阻挡。1949年中华人民共和国成立时，中国共产党的根据地是中国北方和东北。如果你要选择一个城市作为首都，北京一定是最好的选择。东北是中国在20世纪40年代唯一高度工业化的地区，那里可以制造大量武器来维持战争。
总之，中原是统一中国的关键。当军阀强人利用关中的资源控制中原时，都城为长安(西安);当他们凭借中原的资源崛起时，定都洛阳或开封; 当他们可以利用蒙古、东北或华北的资源来控制中原时，他们的首都就会是北京。

Nick Zhao
here is actually couple of reason.
as you see in earlier answers Xi’An is located in a strategic locations with mountain ranges surrounds it, so it is very safe. Here is other reasons it is used as capital city
1. has a nice populous hilly area that is good for grain cultivation, and the area is famous for producing tough troops.
2. Located on top of Sichuan plane, another resource rich area perfect for cultivation. Control Xi’an give you easy access to Sichuan, one of more isolated Chinese areas
3. It is the eastern end of the silk road, keep in mind early ships were not design well enough for long range ocean fare. Land base trade route is the most common.
4. Chinese civilization originated in silted riverbed of Yellow River, so in early Chinese history, most population center are in the North, in modern day Henan, Shangxi produces.
5. Most of Nomad threats are coming northwestern areas, where Xi’an as capital, can provide a base close enough to the military centers.

这里有几个原因。
正如你在之前的回答中看到的，西安位于战略要地，群山环绕，所以非常安全。以下是其他的原因，它被用作首都：
1. 有一个很好的、人口稠密的山区，适合种植粮食，该地区以出产坚韧的军队而闻名。
2. 位于四川之上，又是一个资源丰富的种植区。控制西安可以让你很容易进入四川，这是中国比较孤立的地区之一。
3. 中华文明起源于黄河的淤积河床，所以在中国早期历史上，大多数人口集中在北方，在现代河南、陕西一带。
4. 它是丝绸之路的东端，记住，早期的船只设计得不够好，不适合长途航行。陆基贸易路线是最常见的。
5. 大多数游牧民族的威胁来自西北地区，首都西安可以提供一个离军事中心足够近的基地。

Now here is reason in later period this is no longer the case.
Inadequate food production. Guangzhong plain, while a rich produce area, does not product enough food to support a mega capital city. In Tang period, there is record of emperor and his staff travel to Luoyong, so they can get enough food.
Inadequate transportation, while Xi’an is surrounded by hills that provide defensive, it also created bottleneck for transportation, limit transportation of goods and trade. It does not help that Xi’an is located at higher altitude, which water flow download, so when good has to move to Xi’an, it has be against current, often by manpower only.
Decline of Northern China as population, political and economics center. As stated early China civilization is centered around yellow river, however, after fall of Han, civil war, nomadic invasion ravage Northern China. Much of Chinese elite and population moved south, and now center around Yangtze River. Xi’an while still very capable as a regional center, is too far from new Chinese center.

以下是之后不再是首都的原因：
1. 粮食生产不足。关中平原虽然是一个农产品丰富的地区，但生产的粮食不足以支撑一个超级都城。唐代有记载，皇帝和他的部下前往洛阳，以便获得足够的食物。
2. 交通运输不足，西安四面环山，提供了防御，这也造成了交通瓶颈，限制了货物运输和贸易。西安地处海拔较高，这对西安水运没有帮助。
3. 中国北方作为人口、政治和经济中心的衰落。正如早期中国文明以黄河为中心，然而，汉朝灭亡后，内战，游牧民族入侵蹂躏中国北方。许多中国精英和人口南迁，现在以长江为中心。西安作为区域中心的能力仍然很强，但距离新的中国中心太远了。

Similar to earlier reason, after fall of Rome, Han, Decline of Tang(later Chinese kingdom is more fragments and have less control in the North and on silk road), fragmentation of Abbasid leave silk road countries in political instability, which give rise to silk road on the sea.
Emergency of new Chinese enemies ( Chitan- Liao, Jurchen- Jin, Mongol-Yuan, Manchu-Qing_, those quasi-Chinese kingdom head by non-Han Chinese considered major threats to Chinese proper imperial headed by Han Chinese, since these kingdom were more structured, with developed army systems. They were also located more eastern, shifting center of Chinese defense forces further east.

4. 与之前的原因类似，罗马、汉朝、唐朝的衰落(后来的中国王国更碎片化，对北方和丝绸之路的控制更少)，阿巴斯的碎片化使得丝绸之路国家的政治不稳定，这就产生了海上丝绸之路。
5. 新的中国敌人(契丹辽，女真金，蒙元，满清，那些由非汉人领导的准中国王国被认为是由汉人领导的中国正统帝国的主要威胁，因为这些王国的结构更完善，有发达的军队体系。它们也位于更东部，将中国国防力量的中心进一步向东转移。