Jewish Encyclopedia: Hellenism: "Post-exilic Judaism was largely recruited from those returned exiles who regarded it as their chief task to preserve their religion uncontaminated, a task that required the strict separation of the congregation both from all foreign peoples (Ezra x. 11; Neh. ix. 2) and from the Jewish inhabitants of Palestine who did not strictly observe the Law (Ezra vi. 22; Neh. x. 29)."
