Notes on “The Greek Language” from Interpreter’s Dictionary of the Bible
Koine Greek=Common Greek. It is difficult to clarify set rules/usage universally or even regionally. It was a street language. As with most vernacular language, Koine is vibrant, simple, and lacking in literary sophistication.
Of the four major time periods of changed Greek language, Biblical Greek is found in the Hellenistic Period (300 B.C. -550 A.D.). The Greek New Testament is the best example of Koine, yet many other documents exist.
Factors that simplified and spread Greek:
Political turmoil for centuries before Augustus (instability led to leaving traditions)