Bad news.  The trade business you were running fell apart.  You see, the Roman Empire is over, and now all the trade roads that were kept safe by soldiers are unsafe.  You could try to ship a wagon of your products to the east . . . but it probably will not make it.  So now what are you going to do?  The things you used to do for food and money are gone.  The world has changed, people have left the cities, and there's no leader to run the continent.  You are going to have to come up with a new job in place of trade . . . but what?


Thinking with your brain of today (instead of the brain of a trader living after the end of Rome), you might think that this is easy to solve.  You could just keep trading with the people in your country and earn enough money to buy food for you and your family.  There's only one problem: people do not use the money they did before.  Currency is anything that is used as money.  Today, the US uses dollars and Mexico uses pesos.  Both are just a piece of paper, but you can use them to buy things.  As a trader in the Roman Empire, you would have traded goods for Roman money, but now no one will take that money.  There's also no army to keeps your ships safe and you cannot ship your goods to far away places.  What will you do?


All jobs are based on one simple idea.  You provide a valuable task for someone else, and they give you something valuable in return.  Exchange means to give one thing and get something else back.  You can no longer do this with people who live in far away countries.  Now you need to work for whoever owns the land on which you stand.  You still have hands.  You still have feet.  You can still provide an honest day's work.  What will they pay with if there is no money?


After Rome fell, people left the cities and went to the countryside. They would work the land for lords who would keep them safe in return.  A fief is a piece of land given by a lord to someone else in exchange for them working the land for the lord.  Land was a kind of money and people would work the land that the lord gave to them.  If a king wanted the help of a strong fighter, they would give them some land.  If you were a farmer, a lord would give you land to work and you would give them some of the food you grow.  At any time, the lord could take back the land they gave you.  The only person who really owned the land was the one who also owned the army.  This might be confusing because you cannot just take some land, fold it up, and stick it in your pocket like money.  But the old way of trading was gone, and this is what people had to work with.  So how are you going to get your hands on some of this land?


Now that all your trade routes are gone, you are going to have to use the land under your feet.  Unfortunately, that land belongs to the king who gathered armies and fought for it.  Fortunately, that king has lords and knights, and they need help working the land to grow crops to sell and eat.  Wars and keeping their people safe take up a lot of their time.  An oath of fealty is promising that you will work or fight for another person.  By telling someone in power that you will do whatever they ask of you, they will give you some land to work.  You can grow food on this land, and then you will have to give some of it back to the lord.  


When Rome falls, and your trade ends, all is not lost.  In an age before currency, paper money, when exchange, trading, was the only way to make a living, you still have options.  By making an oath of fealty to a lord, by saying you will do what he asks, you can get a fief, or a small piece of land, that you can work to grow crops and live.  The Roman Empire may be over, but that does not mean you do not have any hope.  In the Middle Ages, the land beneath your feet can be like money in your pocket.  

References:

History For Kids.  "Medieval Economy"  historyforkids.org, 2011.  <http://www.historyforkids.org/learn/medieval/economy/>

The Finer Times.  "Economy in the Middle Ages"  thefinertimes.com, 2012.  <http://www.thefinertimes.com/Middle-Ages/economy-in-the-middle-ages.html>