The Mongol Empire subjugated most of Eurasia in the thirteenth and fourteenth centuries. Tibet was also under the control of the Mongols and the Sakyapa became the ruler of Tibet with the support of the Mongols. However, it is not well known how the Mongol government ruled Tibet. It is also not clear what the Sakyapa did and what kind of levies the Mongol government imposed on the Tibetan people. This is due to the lack of Tibetan records on worldly affairs, which is the common practice in Tibetan writings. Furthermore, the Chinese sources are also reticent about Tibetan affairs during this period. Therefore, it is interesting that a lot of Chinese records on the postal system, the jam(Ch.站), mention about Tibetan monks. These records repeatedly criticized the extremely large number of Tibetan monks invited to Dadu by the Mongol ruling class. They were using post horses lavishly and thus, brought about the breakdown of the Mongol postal system in China.
From the fact that postal households in the Chinese area suffered from compulsory service for the monks from Tibet to Dadu and vice versa, we can deduce that the situation of the Tibetan postal stations might have been the same. What is more important is that because the Tibetan population was small, but the dominions was vast, the situation was worse than in China. We see records that Tibetan postal households became so impoverished that they could not redeem their postal duty. Most of Tibetan condemnations against the Mongols and the Sakyapa regime made mention of the ulag (’u lag, postal horses or postal labor).
As is well known, the Mongol government established thirteen myriarchies in Tibet. What is interesting is that the Archives from China and Tibet which the Wise like: Mirror Illuminating the World (Rgya bod kyi yig tshang mkhas pas dga’ byed chen mo ‘dzam bu gling gsal ba’i me long) in 15th century recorded that several myriarchies in Tibet worked solely for the postal stations. In addition, there were two kinds of postal stations in Tibet: one is large station('jam chen), the other is small station('jam chung).
The biggest problem was that when the monks came back to Tibet, they had enormous amounts of offerings by the Mongol ruling class. For example, in 1270, when Khubilai was initiated from Lama Phagpa, he offered one thousand ding (Ch. 錠) of silver and fifty-nine thousand rolls of silk to Phagpa. Since Phagpa, lots of Tibetan monks were invited to the Mongol court and returned to Tibet with huge offerings from the Mongols and they wanted to carry the offerings to Tibet on the postal horses. Several records mention that some Tibetan monks were found guilty of overloading postal horses with the huge offerings on their way home but absolved soon by the order of the Khan.
The facts that an absolute majority of Tibetan households worked for the postal system and ulag was considered as one of the heaviest burdens imposed by the Mongols show that the maintenance of the postal stations was the most critical duty for the Tibetan people. In addition, it is also noteworthy that the number of households in charge of each of large station ('jam chen) is set at almost 3,000. In some cases, the number of households in the individual myriarchy itself was 3,000, all of whom were entrusted with postal stations. But even when several myriarchies were collected and entrusted with one large station, the Mongols and the Sakya regime also set the number of the households to be in charge of one large postal station at 3,000. Through this, we can say that Mongolian and Sakya regimes saw it appropriate that 3,000 Tibetan households had jurisdiction over one large stations.
Then, who had jurisdiction on the Tibetan postal system? It was Khubilai’s high official who came to Tibet and decided the locations of Tibetan post stations and the Mongol court in Dadu sent alms to Central Tibet when the postal households fell into poverty. However, the pönchen (lay governor) of the Sakyapa sect also conducted a census in Tibet together with the Mongol officials before the postal system came into effect. Peljor Zangpo’s lists were also from a pönchen’s archives. These facts show that the Sakya regime had jurisdiction over the system, too. Even Jangchub Gyeltsen (Byang chub rgyal mtshan, 1302-1364), who won over the Sakyapa sect and ruled over Central Tibet in the middle of the fourteenth century, asked the Mongol court for a temporary tax and labor exemption in Tibet while he mentioned that he would continue to maintain postal system.
In conclusion, the Sakyapa and the Mongols worked together to maintain the Tibetan postal system. And the compulsory labor and supply of horses and foods for the postal stations were the most critical duty imposed to Tibetan people by the Mongols.