Final answer:
The so-called "third phase" of Greek colonization, during the Archaic period, refers to an era of Greek expansion that established numerous colonies strategically located near the sea to facilitate trade and spread Greek culture following the Dark Age.
Step-by-step explanation:
The period often referred to as the age of Greek colonization is labeled as the "third phase" because it represents a distinct era of Greek expansion, following the recovery from the Dark Age. During this phase, which coincides with the Archaic period (around 800 BCE - 490 BCE), the Greeks embarked on widespread colonization due to agricultural needs caused by a growing population and scarce resources in Greece. These colonies extended from the western Mediterranean to the Black Sea and were integral in spreading Greek culture, establishing trade networks, and sharing Greek values. This phase was preceded by initial settlement and recovery periods, hence being termed the "third phase" of colonization.
Greek colonies were strategically established near the sea, allowing them to flourish as economic outposts and enabling trade with a variety of cultures, from the Celts to the Egyptians. Colonists sometimes integrated with local populations, while other times, they maintained strong ties with their home polis. The practice of dividing land into equal lots and associating citizenship with participation in governance reflects the evolving socio-political concepts within these new Greek states.