Why did the Greek monarchy fall apart in the 7th century BC?

Extensive and close trade ties have further expanded overseas markets, making the Greek world connect with eastern civilized areas such as Egypt, Syria and Babylon in the east, Africa in the south, the Black Sea in the north and the inland of Central Europe and Western Europe in the west, forming the largest Mediterranean trade circle and economic circle that has never been seen before, interwoven with the mainland and connected with things, far exceeding the scale of Aegean civilization. The activities of the Heaven and Earth Society also had a positive political and cultural impact on the Greek city-states. It contributes to the stability of the citizens' collective and the consolidation of the city-state system. With the development of economy, the industrial and commercial slave class has also strengthened the power of the civilian camp, which is helpful to the struggle of the civilians against the nobility and the establishment of democratic politics. The cultural exchange that developed almost simultaneously with the colonial movement greatly promoted Greece to absorb the fruits of oriental civilization. It not only made the 7th century BC, when the colonies were prosperous, known as the "Orientalization Period" in Greek history, but also broadened the horizons of the Greeks, enriched their understanding of the world and history, and helped them explore a scientific way to gain wisdom through comparative analysis. Early Tyranny Politics With the development of overseas colonization, the aristocratic autocracy that existed in the early days of the formation of Greek city-states was challenged, and the struggle of civilians against aristocrats became increasingly fierce. At this time, the nobles mostly established their privileges by ancient clan relations. Their main tool is the aristocratic meeting evolved from clan and tribal councils. Through this meeting, they mastered the military, political and financial power of the city-state, and the citizens' meeting was in name only. They own many slaves and large tracts of land, and oppress ordinary people, mainly small farmers, through land annexation and usury exploitation. At that time, debt slaves prevailed, and citizens who were bankrupt in debt often became debt slaves or even sold abroad. Thus, it is the inevitable trend of the development of city-state politics that civilians oppose aristocratic oppression. What's more, the economic development brought by colonization has also made a few civilians who run industry and commerce rich and become new industrial and commercial slave owners. They generally can't attend aristocratic meetings, their political status is relatively low, and they are also very dissatisfied with aristocratic autocracy. Therefore, they often approach civilians and oppose nobles in political struggles. However, under the specific conditions at that time, the struggle between civilians and nobles did not directly lead to the democratic politics in which civilians were in power, but instead gave the tyrant who used civilian power to establish personal rule an opportunity.