Question shift into:
How did the Mongols encourage trade?
Mongols drastically reduced agricultural taxation, often by orders of magnitude. That was a typical first move in recently captured nations, and it was the primary factor in how quickly their dominion grew. For the most part, the same strategy was used, with a few outliers, in local business and industry. During the first century of the Mongol period, literally hundreds of new towns and communities arose, demonstrating the effectiveness of their strategy.
Naturally, the Mongols required a second source of revenue to maintain a thriving economy. Long-distance commerce was charged in its place. Since they were completely aware of its importance, the Mongols actively promoted trade, which eventually became the foundation of their dominance.
They made significant investments in the commerce networks. In a brief period of time, thousands of caravan-serais were constructed. Between the Soviet city of Orenburg and the Mangyshlak peninsula in Kazakhstan, we can still see the remains of one such network. Over the course of about 2,000 km, 90 wayside inns were constructed. The distance between them was 25 km, or precisely one day's travel for a convoy. Caravan-serais were constructed as a public project and nearly concurrently because they were nearly identical and made in accordance with a specific master plan. We know from written records that more than just drink, sustenance, and shelter were offered. It was required to use services like notaries and translators. Large caravan-serais were situated every 100 km to allow for extended relaxation, these were in fact small towns.
The primary issue was security. In reality, the theft and murder of traders who were under the protection of the Mongols in the Central Asian city of Otrar marked the beginning of the Mongols' westward advance. Numerous sources from the West and the Muslim world claimed that the Mongol countries had an exceptionally high level of safety. The central authority appears to have even insured the damages if they happened on the highway. We are aware of at least one case in the fourteenth century when a merchant from Genoa took the Khan of the Golden Horde to justice over the theft of his goods while on the way, and the Khan was compelled to pay the merchant in full.
Which brings us to a legal framework there. Mongols combined their own Yasa system with regional common law in a rather peculiar way. Islamic law was subsequently adopted almost everywhere. However, it appears that local rules, which were typically very benevolent to merchants, control long-distance commerce. If they had paid taxes and fees.
The Mongol empire's primary source of revenue may have been customs duties on international commerce. Their concentrations varied, ranging from 0% for silver to 100% for specific types of unprocessed skins. It is reasonable to assume that a retailer paid, on average, between 2% and 4%. Sometimes, but very infrequently, some products were completely embargoed. The only significant benefit was that for the entire transcontinental journey, duties were only required to be paid once at a point of entry.
The Mongol government was also very busy in lending to merchants and investing in trade organizations. The typical interest rate was 0.8% per month, which was likely the lowest available at the time.
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