The answer is probably "spices." "Salt" is another possibility.
The most important spice during the Middle Ages was black pepper. It was a very valuable commodity in the European spice trade.
Silks and spices were prized during the Middle Ages. The trade was largely controlled by the Venetians. More indirectly, for most Europeans, it was controled by Arabs and the Byzantines.
Oil.
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The troy ounce supposedly got its name during the Middle Ages for an annual fair held in Troyes, France. A troy ounce weight is equal to about 1.1 avoirdupois ounces, 480 grains, or 31.04 grams.
In the Middle Ages, the people used to salt meat to keep it fresh for later, as salt is a preservative and protects against bacteria, fungi, and insects. Therefore, they used to spice their food heavily when they ate it to camoflage the heavy and therefore unpleasant taste of the salt.
Embalming has been practiced in one form or another for thousands of years. It was not much used in medieval Europe, however. Frederik Ruysch is noted as the originator of arterial embalming (replacing the blood with a preservative) in the 1600s.
In the world of finance there are many confusing terms and concepts, but thankfully commodities are not among them. When hearing the words "commodity prices", all an economist is really talking about is the cost of goods. Granted, most economists are talking about major commodities when referring to commodity prices, but technically a commodity can be anything consumers purchase. The main reason that commodities are so important when regarding the economy is that they form the backbone of practically any nation's wealth. One particular commodity that very much controls the wealth in the Middle East is oil. It is for this reason that we so often hear about the rise and fall of oil prices. Another reason why we often hear about commodities is that they are far more volatile compared to a nation's standard economic setup. Volatility is a measurement of how dramatically the commodity price of a particular good changes. This is an important value because it can be an indirect way of judging how stable an economy is. Naturally, commodity diversity will result in a more stable economy. Returning to the oil example, it is easy to see why the Middle East is regarded as a slightly unstable area. Their heavy reliance on oil means that the fall and rise of oil directly affects their economic standing. Another important value to understand when speaking about commodity prices is the rate of measurement per item. Many would understandably think that an item would be measured perhaps by its mass or its volume, but unfortunately this is not so. It isn't uncommon to hear of oil being referred to in barrels, or precious metals in carats. The simple fact of the matter is that there is no uniform method of measurement, and the measuring procedure varies quite a bit from commodity to commodity. In a nutshell, commodity prices are important to understand because they both affect the price of individual goods and they also indicate how a particular commodity affects a nation's economy. Commodity prices have high volatility, and greater diversity ultimately makes for greater stability in an economy.
because they are naturally rich in oil, and they understand how precious oil is and will be.
YES! Oil is a global commodity. They pay the same price as anyone else does on the goods, and do not control where it comes from.
I am not sure if it is exactly 300 billion dollars, but the answer you are looking for is PETROLEUM.
The capital of Egypt during the middle age was Thebes