How did the desire for trade with asia encourage the exploration of the americas?

Since the Asians prided themselves on being self sufficient, the Europeans didn't have anything to trade with them. However, they wanted Asian goods, because they didn't know how to produce things like silk and tea in Europe. Therefore, they went off to explore the Americas to find new products. Obviously, the Asians didn't have American goods yet, so the Europeans wanted to go over there and get them so that way they would have something the Asians desired. One of the biggest discoveries in America were the silver mines, such as Potosi. China especially put a high value on silver, since they used it for their coins. Once the Europeans acquired this silver, China was willing to trade with them.

What was the length to begin with?