Thanks to the increasing economy had the way of living of the upper classes increased. This put more pressure on the lowest classes, which were already neglected. The laws, which were in the hands of the nobility, became an excellent way to control the lower classes. That is why it is not surprising that they demanded legal justice and a better economical protection. In many Poleis was decided to listen to their demands, and the laws were reformed and written down.
Tyrants take the power.
Such a tyrant was always a noble himself, though he was an enemy of the same nobility and its monopoly. The word tyrant, a Lydian word, did not have the same bad meaning as today. A tyrant was simply a single man who ruled a city. In many cities such a tyrant took over the power, and often their actions were good for the cities. By breaking the privileges of the upper class they prepared the cities for some form of more democratic government.