The second reason is that in the Western Han Dynasty, it has entered the era of cold weapons. At this time, the ability of mining minerals in the Western Han Dynasty was also very strong. According to historical records, at that time, the Western Han Dynasty had set up official posts specializing in mining, and the number of such official posts was particularly large, so the Han Dynasty was able to mine some gold mines by itself, because the state treasury had a very large amount of gold storage at that time.
The third reason is that during the Western Han Dynasty, many western countries had some trade with the Western Han Dynasty. For example, the historical secretary of Rome said that Rome traded with the Western Han Dynasty every year, such as buying some silk from the Western Han Dynasty and so on. Every year, the amount of gold that Rome poured into the Western Han Dynasty will reach more than 5 tons, which is actually quite amazing.
In fact, many historians in history will think that there are many gold reserves in the Western Han Dynasty. For example, in the battle between Liu Bang and Xiang Yu, Liu Bang used 42,000 gold to alienate the relationship between Xiang Yu and Fan Zeng. It was also because of this gold that Xiang Yu doubted Fan Zeng, which eventually led to Fan Ceng's resignation and return home. Later, Fan Ceng died of illness on his way home. After Xiang Yu lost his right-hand man, he committed suicide in Wujiang two years later. Therefore, the establishment of the Western Han Dynasty was actually based on these huge amounts of gold.