Final answer:
The Greeks were unified in defense of their culture and way of life due to external threats. They recognized each other as fellow Greeks and shared a common language, religion, and culture.
Step-by-step explanation:
The Greeks were unified in defense of their culture and way of life due to external threats. They recognized each other as fellow Greeks and shared a common language, religion, and culture. Additionally, they participated in panhellenic sanctuaries and festivals that encouraged interaction and competition.