The expansion and maintenance of the trading routes did not derive from an ideological commitment of the Mongols to commerce and communication in general. Rather, it stemmed from the deeply rooted system of shares, or khubi, in the Mongol tribal organization that had been formalized by Genghis Khan. Just as each orphan and widow, as well as each soldier, was entitled to an appropriate measure of all the goods seized in war, each member of the Golden Family was entitled to a share of the wealth of each part of the empire. Instead of the salary paid to non-Mongol administrators, the higher-ranking Mongol officials received shares in goods, a large part of which they sold or traded on the market to get money or other commodities. As ruler of the Ilkhanate in Persia, Hulegu still had twenty-five thousand households of silk workers in China under his brother Khubilai. Hulegu also owned valleys in Tibet, and he had claim on a share of the furs and falcons of the northern steppes, and, of course, he had pastures, horses, and men assigned to him in the homeland of Mongolia itself. Each lineage in the Mongol ruling family demanded its appropriate share of astronomers, doctors, weavers, miners, and acrobats.
Khubilai owned farms in Persia and Iraq, as well as herds of camels, horses, sheep, and goats. An army of clerics traveled throughout the empire checking on the goods in one place and verifying accounts in another. The Mongols in Persia supplied their kinsmen in China with spices, steel, jewels, pearls, and textiles, while the Mongol court in China sent porcelains and medicines to Persia. In return for collecting and shipping the goods, the Mongols in China kept about three-quarters of this output for themselves; nevertheless, they exported a considerable amount to their relatives in other areas. Khubilai Khan imported Persian translators and doctors as well as some ten thousand Russian soldiers, who were used to colonize land north of the capital. The Russians stayed as permanent residents, and they remained in the official Chinese chronicles until last mentioned in 1339.
Despite political disagreement between contending branches of the family over the office of Great Khan, the economic and commercial system continued to operate with only brief pauses or detours because of sporadic fighting. Sometimes even in the midst of war, the fighting sides allowed the exchange of these shares. Khaidu, the grandson of Ogodei Khan and the ruler of the central steppe, was often in rebellion against his cousin Khubilai. Yet Khaidu also had extensive holdings of craftsmen and farmers around the Chinese city of Nanjing. In between sessions of fighting with Khubilai Khan, Khaidu would claim shipments of his Nanjing goods, and, presumably in exchange, he allowed Khubilai to collect his share of horses and other goods from the steppe tribes. The administrative division of the Mongol Empire into four major parts—China, Moghulistan, Persia, and Russia—did nothing to lessen the need for goods in the other regions. If anything, the political fragmentation increased the need to preserve the older system of shares. If one khan refused to furnish the shares to other members of the family, they would refuse to send him his share in their territories. Mutual financial interests trumped political squabbles.
The constant movement of shares gradually transformed the Mongol war routes into commercial arteries. Through the constantly expanding ortoo or yam, messages, people, and goods could be sent by horse or camel caravan from Mongolia to Vietnam or from Korea to Persia. As the movement of goods increased, Mongol authorities sought out faster or easier routes than the older traditional ones. Toward this end, Khubilai Khan launched a major expedition in 1281 to discover and map the source of the Yellow River, which the Mongols called the Black River. Scholars used the information to make a detailed map of the river. The expedition opened up a route from China into Tibet, and the Mongols used this as a means of including Tibet and the Himalayan area in the Mongol postal system. The new connections did more to connect Tibet—commercially, religiously, and politically—with the rest of China than anything else during the Mongol era.
During military campaigns, Mongol officials exerted a conscientious effort to locate and appropriate maps, atlases, and other geographic works found in enemy camps or cities. Under Khubilai’s rule, scholars synthesized Chinese, Arab, and Greek knowledge of geography to produce the most sophisticated cartography known. Under the influence of the Arab geographers brought in by Khubilai Khan, particularly Jamal al-Din, craftsmen constructed terrestrial globes for Khubilai in 1267, which depicted Europe and Africa as well as Asia and the adjacent Pacific islands.
Despite the initial reliance of commerce on routes created through military conquest, it soon became obvious that whereas armies moved quickest by horse across land, massive quantities of goods moved best by water. Mongols expanded and lengthened the Grand Canal that already connected the Yellow and Yangtze Rivers to transport grain and other agricultural products farther and more efficiently into the northern districts. Adapting Chinese engineering and technology to new environments, they built water projects throughout their territories. In Yunnan, the Mongol governor created a dozen dams and reservoirs with connecting canals that survived until modern times.
The failed invasions of Japan and Java taught the Mongols much about shipbuilding, and when their military efforts failed, they turned that knowledge to peaceful pursuits of commerce. Khubilai Khan made the strategic decision to transport food within his empire primarily by ship because he realized how much cheaper and more efficient water transportation, which was dependent on wind and current, was than the much slower land transport, which was dependent on the labor of humans and animals that required constant feeding. In the first years, the Mongols moved some 3,000 tons by ship, but by 1329 it had grown to 210,000 tons. Marco Polo, who sailed from China to Persia on his return home, described the Mongol ships as large four-masted junks with up to three hundred crewmen and as many as sixty cabins for merchants carrying various wares. According to Ibn Battuta, some of the ships even carried plants growing in wooden tubs in order to supply fresh food for the sailors. Khubilai Khan promoted the building of ever larger seagoing junks to carry heavy loads of cargo and ports to handle them. They improved the use of the compass in navigation and learned to produce more accurate nautical charts. The route from the port of Zaytun in southern China to Hormuz in the Persian Gulf became the main sea link between the Far East and the Middle East, and was used by both Marco Polo and Ibn Battuta, among others.
En route, the ships also called at the ports of Vietnam, Java, Ceylon, and India, and in each place the Mongol representatives encountered more goods, such as sugar, ivory, cinnamon, and cotton, that were not easily produced in their own lands. From the Persian Gulf, the ships continued outside of the areas under Mongol influence to include regular trade for a still greater variety of goods from Arabia, Egypt, and Somalia. Rulers and merchants in these other areas outside the Mongol system of influence did not operate within the system of shares in the Mongol goods; instead, the Mongol authorities created long-term trading relations with them. Under Mongol protection, their vassals proved as worthy competitors in commerce as the Mongols had been in conquest and they began to dominate trade on the Indian Ocean.