Most Shield rocks were formed well over a billion years earlier, during the very first chapter of the planet's history known as the Precambrian era.

This time became known as the era of New Imperialism.

The Jews knew it as the "era of contracts", and used it in Europe until the 15th century.

This period is known as the paleolithic era.

The years between 1985 and 1989 became known as the "die hard" era.

It was the middle of what became known in the window coverings industry as the mini-blind era.

The island had entered what would later become known as the open era.

This system of dating is also known as the "Hebrew era".

The 1830-1850 period later became known as the era of Jacksonian democracy.

The 16th century is known as the era of mangalakavyas on chandi, for it was in this period that these gained widest currency.