The reforms that Solon initiated dealt with both political and economic issues. The economic power of the Eupatridae was reduced by forbidding the enslavement of Athenian citizens as a punishment for debt, by breaking up large landed estates and freeing up trade and commerce, which allowed the emergence of a prosperous urban trading class. Politically, Solon divided the Athenians into four classes, based on their wealth and their ability to perform military service. The poorest class, the Thetai, (Ancient Greek ?????) who formed the majority of the population, received political rights for the first time and were able to vote in the Ecclesia (Assembly). But only the upper classes could hold political office. The Areopagus continued to exist but its powers were reduced.
The new system laid the foundations for what eventually became Athenian democracy, but in the short-term it failed to quell class conflict and after 20 years of unrest the popular party, led by Peisistratus, a cousin of Solon, seized power (in 541 BC). Peisistratus is usually called a tyrant, but the Greek word tyrannos does not mean a cruel and despotic ruler, merely one who took power by force. Peisistratus was in fact a very popular ruler, who made Athens wealthy, powerful, and a centre of culture, and instituted Athenian naval supremacy in the Aegean Sea and beyond. He preserved the Solonian constitution, but made sure that he and his family held all the offices of state.
Peisistratus died in 527 BC and was succeeded by his sons Hippias and Hipparchus. They proved to be much less adept rulers and in 514 BC, Hipparchus was assassinated in a private dispute over a young man (see Harmodius and Aristogeiton). This led Hippias to establish a real dictatorship, which proved very unpopular and he was overthrown in 510 BC. A radical politician with an aristocratic background named Cleisthenes then took charge, and it was he who established democracy in Athens.
The reforms of Cleisthenes replaced the traditional four "tribes" (phyle) with ten new ones, named after legendary heroes and having no class basis; they were in fact electorates. Each 'tribe' was in turn divided into three 'trittyes' and each trittys had one or more demes, which became the basis of local government. The tribes each elected fifty members to the Boule, a council which governed Athens on a day-to-day basis. The Assembly was open to all citizens and was both a legislature and a supreme court, except in murder cases and religious matters, which became the only remaining functions of the Areopagus. Most offices were filled by lot, although the ten strategoi (generals) were elected. This system remained remarkably stable and, with a few brief interruptions, it remained in place for 170 years, until Philip II of Macedon defeated Athens at the Battle of Chaeroneain 338 BC.