For sources I would suggest looking at the recommended booklist. If you want any more questions about the Mongols answered I'm your man. Unless its China then I'll summon /u/Jasfss .

Ok on the Mongols as a unifying force. They certainly were in a number of ways. Firstly their trade friendly policies made travel significantly easier. They helped provide incredible trade routes to trade along. Banditry was ruthlessly dealt with and ceased to be a major problem, perhaps because the former raiders were now the guards. Furthermore there was the yam a system of way points set up at 25 to 30 miles apart complete with fresh horses and supplies. This and other trade friendly practices such as the ortagh investment system would have improved links across Eurasia.

Furthermore we see the transfer of knowledge from different areas of the empire on an unprecedented scale. The Chinese and Islamic world benefited from each others knowledge particularly in the areas of cartography, medicine and astronomy. The Mongols actively encouraged this. In Iran Hulagu built and observatory and recruited Chinese scholars to work in it. We also see a hospital in Tabriz that made use of Chinese medical methods alongside local ones. Meanwhile in China we see new government departments set up to study foreign astronomy and medicine.

On the arts side under the Mongols, we see a cultural flowering as various styles and techniques were transferred along the Silk Road. In the Ilkhanate, Persian and Buddhist painting styles came together in imperial workshops. In Tabriz, there was a major Chinese quarter where various Chinese artisans lived, spreading new styles. In China, artisans benefitted from new materials, importing cobalt from Iran to create the first iconic blue and white Chinese porcelains . The Mongols also took an active role in China, sponsoring the Hanlin painting academy as well as various theatrical productions with the result that the Yuan period is seen as the golden age of Chinese theatre.

/u/rakony , as always, is the Mongol man. Certainly, Mongolian rule stretched far and wide, and after the fracture, YMMV depending on which Khan you lived under.

The Yuan dynasty in China was established under Kublai Khan. Prior to this, the region of China existed under three states for the most part: the Jin Dynasty in the north and the Song in the south being the big two, and the Western Xia in the...west. The Song had previously been in control of both the northern and southern regions, but the northern lands were conquered by two non-ethnic Chinese peoples: first the Liao Dynasty comprised of the Tanguts and then the previously mentioned Jin Dynasty made up of the Jurchen, who were the ultimate staying force before the Mongol invasions.

With China proper being split between the Jin and the Song (the Song containing ~80% of the ethnic Chinese population), there were efforts by the Song to sort of "amplify" their "Chinese-ness" by way of an intense focus on developing Southern Chinese culture. During the Song (in both the Northern Song and Southern Song periods), paintings rose to great prominence, mainly coming in two popular flavors: landscape Shanshui (山水, mountains and water) and Huaniao (花鸟, birds and flowers). As you might expect, the subjects of these styles follow closely with their names. But why specifically these kinds of styles? Again, back to the focusing on culture, there was lots of neo-confucian work done in this time period. These aspects of focusing on natural themes comes from the study of Li (理) which in this sense, can be translated as "natural patterns" as opposed to the other force that many are familiar with of Qi (气). I like to include pictures when I can to break up these boring words, so here's an example titled "Travelers Among Mountains and Streams", of the 山水 style. In it, there are humans in the picture, but they're not the main focus, symbolizing man has a place in nature, but is not necessarily the focus.

In the north, under the Jurchen, a different cultural focus developed, specifically the Sanqu (散曲), a type of "song poem". These poems are similar to the very ancient poems collected in the Shijing (诗经) from mostly the Western Zhou Dynasty existing in the 11th century BC to around the 7th century BC. These are oral tales using metrical patterns and sung, sometimes with an instrument accompaniment. The Sanqu, growing in the Jin dynasty and flourishing in the Yuan, unlike the poems in the Shijing, were of non-ethnic Chinese culture, using northern vernacular and highly colloquial, unlike the classical Chinese in the Shijing and most Chinese literature.

So, in the sense of a kind of "evolution" of culture, the Yuan dynasty certainly catalyzed the meshing of non-Chinese/northern Chinese culture with the south, bringing those two distinct cultural elements I discussed closer together, ending the dynastic separation, and spreading them throughout the region. Unfortunately, I wouldn't say that most of the Chinese in the south were happy with Mongol rule or recognized any benefits. I discuss that part more here, but basically, the Yuan dynasty was a martial force, allowing little ethnic Chinese involvement in the actual governance (indeed, there was an abolishment of the imperial examinations altogether).

Aren't they both truths though? I'll neglect to use the term "barbarians" as it holds a negative connotation and certainly isn't suitable, but did the Mongols not rape, pillage, and burn their way to the largest empire in recorded history? I don't think anyone would argue that, under the Mongol's reign, the spread of culture, trade, knowledge, and weaponry was immense and it was the first instance of truly "connecting" the east with the west but the means in which they did so were very, very violent.

Furthermore, I think "unifying" is not the correct word but rather "connecting" would be better suited.

Thoughts?