But to answer your afrocentric question, the different empires each had their own established slave networks and infrastructure in Africa (logistics as has already been stated), see: 1  Arab slave trade. 2  Barbary slave trade. 3  Slavery in the Ottoman Empire.
Asparagus is a vegetable belonging to the lily family, which also includes onions, leeks and garlic. Eat asparagus as part of a heart-healthy diet, as it contains no fat, no cholesterol and very little sodium.
Both olive oil or vegetable oil work great, so use whichever you prefer. Olive oil has a slightly different taste, but it goes great with asparagus. Just use about a teaspoon per pound of asparagus, and toss the asparagus in the oil to make sure it's evenly coated. You can use extra oil to help the asparagus brown more quickly. I'm not a huge fan of using lots and lots of oil though.