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why did the ottoman empire close the silk road
You've heard it: in 1453 the Ottomans took Constantinople, shut the Silk Road, and forced Europe to sail around Africa. That story is mostly a myth.
In fact the Ottomans were businessmen. A sultan wants caravans arriving, because every load pays customs. They taxed the trade, they did not close it.
Within a year, in 1454, Sultan Mehmed the Second signed a treaty letting Venice trade freely. And most spices reached Europe through Egypt and Syria anyway.
So how did spice really travel? From Asia across the Red Sea to Mamluk Egypt, then Venice, then Europe. Every hop added a tax and a markup.
Then in 1498 Vasco da Gama reached India by sea. Portugal could skip every middleman, Venice, Egypt and the Ottomans too. In 1517 the Ottomans took Egypt, and spice kept flowing.
So why did overland trade fade? The Mongol peace broke up after 1368, ships carried more per coin, and Europe wanted to skip middlemen. The Ottomans were tollkeepers, not gatekeepers.
The Silk Road never slammed shut in 1453; it slowly lost out to ships, and the Ottomans mostly collected the tolls.