The direct cause of the old shipping routes do not work

The direct reason why the old shipping routes did not work:

1, economic reasons: around the 15th century, the development of the commodity economy and the emergence of the bud of capitalism in Western European countries.

2. Social reasons: Europeans fervently pursued gold and silver as currencies, especially the "Marco. The circulation of the "Acts of Polo" induced people to seek gold in the East.

3, the direct cause (commercial crisis): Ottoman Turkey to control the traditional trade routes, resulting in the impassability of the trade routes, triggering a commercial crisis.