Ghengis khan had rapidly expanded the mongol zone of influence during his conquests while keeping his army intact and his new lands subjugated and under his control. However, I am curious how Ghengis khan had organized and planned the logistics of his far reaching invasions and how he administrated his new holdings. The vast swaths of land he controlled were often populated and keeping control over non core territories during the Middle Ages was a difficult thing to do. So I guess my question is how did Ghengis khan and his later predecessor, ogedei, hold onto their empire and plan the logistics of their invasions?
I cover some of the logistics and tactics of the Mongol army here. And then I talk about some basic taxation and administration here.
The administration aspect of my second post is really broad, and it was because the question was broad in and of itself and diving into specifics can bore some people; however, I will expand a bit further for you since you're wondering how new holdings and probably older but more recent holdings were administered.
So, the Mongols get a lot of credit for rapid adaptation and rightly so; initially, under Genghis Khan, they would govern by using their military as a basis for their organization of society. Using this method they could get tribute from the more recently conquered lands; however, this wasn't a long term solution and as time went on, the Mongols realized the importance of taxation. Genghis Khan relied on some of his subjects that were more closely related, such as the Khitans who had recently ruled Northern China but were overthrown by the Jurchen even more recently. Likewise, in Central Asia they relied on the Kara-Khitai for the same reasons. These groups of people were great bridges for the Mongols in my opinion, though the Khitans were proto-Mongolic people, they had become more and more Chinese-like and although the Kara-Khitai were Turkic, they had become more and more Persian-like. You can see how these people could have been useful to the Mongols just from the bridge perspective I mentioned. Despite all this, the Mongols still appointed governors to these areas. Some sources claim that these governors were rotated in and out of these regions, which doesn't surprise me at all to be honest because Genghis Khan believed that the world could be conquered and ruled from horse back, and as history tells us, nomadic people were very prone to adopting sedentary like society when exposed to it.
As the Mongol Empire continued to expand and last longer this evolutionary process continued through the administration of Ogedei, (the second ruler) and by the time of Mongke (the 4th ruler), we see him trying to make the Empire more centralized and more bureaucratic, as he creates "viceroy" like positions to oversee the duties of these governors and census-takers once the Empire moved to a tax based system. Obviously as the Empire grew it was important to maintain stability through trade and agriculture as well, this was important especially because the Mongols controlled the sedentary peoples.
I'm not sure if you meant to type predecessor, or if you meant successor; however, Ogedei is the 3rd son of Genghis Khan and will succeed him in ruling the Empire. In 1229 at the Kurultai, the Mongol nobility will vote to elect Ogedei as the new Great Khan of the Empire. Now, I'm a firm believer that Ogedei was simply brilliant - many have made the case for the youngest son, Tolui, or the oldest, Chagatai, and I can see where they are coming from, but I just find Ogedei from an administrative perspective to be great. Genghis Khan typically did everything from a military camp, sometimes you couldn't even find the man as he was always on the move. Ogedei knew that this would cause a problem in this ever evolving system, especially during the transition from tribute to tax based, so one of his first decrees was to have an imperial capital. Symbolism aside, it was nice not only for the Mongols but also their subjects as they now had a set place where they could deliver their taxes, show up for meetings and later, accommodate travelers and merchants . And thus, in 1235, Karakorum was to be constructed. I'd like to mention also that this didn't mean Ogedei had decided to settle, he continued to live a nomadic life-style. Ogedei realized that there was no way to implement his father's Yasa law on other people, so he implemented religious tolerance in what was now a multi-religious and multi-ethnic Empire, though I warn you - when I mean religious tolerance there is more emphasis on the word tolerance here. One detail one should remember, is that the Mongols considered other populations to be lesser than their live-stock and I highly doubt their opinion changed simply because they had conquered them (up to this point at least). Does this mean that everyone needed to be Mongol? Of course not, and Ogedei knew this, so he tolerated these other people.
Ogedei also invested heavily in infrastructure. These are not all new projects, some of them were expansions of what his father had begun. For example, stations were placed around the regions of Mongolia in which messengers could ride through very quickly and bring news to the Khan ASAP, and likewise he could send news out. What Ogedei did was simply expand it by creating stations that reached farther as the Empire grew and sped up the process by giving these people "licenses" or "passports" I suppose would be the better word. A rider could show up to one of these stations, flash their passport, swap out his horse and continue along. This made it possible to get news to everyone much more quickly.