golden age

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A period of great peace, prosperity, and happiness.
• noun Greek & Roman Mythology The first age of the world, an untroubled and prosperous era during which people lived in ideal happiness.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A happy age of peace and prosperity.
• noun A time of great progress or achievement in a particular field.
• noun The Golden Age.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any period (sometimes imaginary) of great peace and prosperity and happiness
• noun (classical mythology) the first and best age of the world, a time of ideal happiness, prosperity, and innocence; by extension, any flourishing and outstanding period
• noun a time period when some activity or skill was at its peak