An enormous improvement in iron metallurgy between the mid-eighth and mid-seventh centuries made work faster and more efficient.
Iron was the metal and was used for such things as wheels, ploughs, and swords.At the same time, the population boomed and the Greeks switched from an economy based on pasturage to farming. Unfortunately, there wasn't enough land for everyone.
What land they had was divided among the sons, and as the generations subdivided, the allotments shrunk to the point where they couldn't produce enough food for their families. In search of new land, mainland Hellenes (Greeks) started colonies. These sent back to the homeland raw materials, foodstuff, and metals. In exchange, the colonies received finished products. Attica (known mainly for Athens) had a greater land mass than other areas and as a result came late to the need for colonizing.
Where the Greeks couldn't take resources peaceably, they took them by force. This need for soldiers increased the importance of the individual small farmer-soldier known as a hoplite.
Thomas Martin Overview 5.3
"A population as large as that of classical Athens could be supported only by the regular importation of food from abroad, which had to be financed by trade and other revenues."
