Caerlaverock Castle was built to control trade in early times.

And making money was only possible for those who controlled trade.

Police roadblocks were set up around the country to control internal trade.

Those who control trade will always have a powerful hold upon the rulers.

The walls were built to control trade and also to stop the city from being flooded.

"In some ways, the genetics issue is just an excuse to control trade."

A function which includes controlling trade and policing the System.

The customs house from the 16th century was constructed to control trade on the lake.

To achieve this goal, the Federal government set up structure in order to control foreign trade.

Through this bank the Prussian government controlled investment, trade and the issue of paper money.