The core of the Hellenistic culture promulgated by the conquests was essentially Athenian. The close association of men from across Greece in Alexander's army directly led to the emergence of the largely Attic-based "koine", or "common" Greek dialect. Koine spread throughout the Hellenistic world, becoming the lingua franca of Hellenistic lands and eventually the ancestor of modern Greek. Furthermore, town planning, education, local government, and art current in the Hellenistic period were all based on Classical Greek ideals, evolving into distinct new forms commonly grouped as Hellenistic. Also, the New Testament was written in the Koine Greek language. Aspects of Hellenistic culture were still evident in the traditions of the Byzantine Empire in the mid-15th century.