Classical historians believe…

Even the relatively sober biographies of Alexander the Great, for example, that are still in existence date from the late first and early second centuries AD. Yet Alexander died in 323 BC, so there is a gap of about five hundred years before his biographers Plutarch and Arrian wrote their books about his life. Both writers, however, acknowledge copious indebtedness to previous written sources, and classical historians believe they can derive in great detail accurate historical information about Alexander from these works, while at the same time recognizing they are no means flawless.

Craig Blomberg, from Making Sense of the New Testament, p. 27