Shanxi merchants
The most plausible explanation of the financial prominence of the province of Shanxi states that its salt works at Xiechi Lake fostered mercantile activity that would ultimately need banks. A state salt monopoly held by the imperial government persisted, with only a few minor interruptions, from the Han dynasty until the year 1370 during the second year of the Ming dynasty. In 1370 the army of the Ming began using its salt rights, known as "yan yin", which were initially redeemable only at the Xiechi Lake, to pay for transporting provisions to Chinese soldiers stationed on the Great Wall. As the Shanxi merchants were handling this lucrative business from its very beginnings, they managed to get a piece of the Ming state's monopoly and the imperial government quite likely netted more revenues of the salt monopoly because of higher overall efficiency. This policy that benefited the Shanxi merchants remained in effect long enough for them to accumulate a substantial amount of wealth for themselves. This hypothesis regarding the rise of the Shanxi merchants also accords with evidence that the region comprising the current Shanxi province was not an important commercial centre until the reign of the Ming dynasty.