Along with trade, the Minoans also invented coins and money. Sometimes, they would also exchange their products with expensive clothes and jewelry from the Middle East, bringing nice gifts back home. They also developed a great urban planning system with cisterns, paths, walls and sewage system. Their kings would live a luxurious life in nice palaces and would frequently organize festivals. All citizens participated in these festivals, which also included shows with bulls. That is why the bull is the symbol of the Minoan civilization.