Britain's Magna Carta and the U.S. Constitution may spring to mind as great foundations of modern government, but the much older Cyrus Cylinder has been described as the very "first declaration of human rights."

The 2,600-year-old artifact is a fairly small, baked, clay object covered in cuneiform script, whose size belies its importance. What it says about a key moment in history provides important lessons in tolerance and justice even today, many millennia later.

"It's an astonishing statement of how you run a multicultural, multi-faith community,"said Neil MacGregor, the director of the British Museum, where the Cyrus Cylinder is part of the permanent collection.

Christiane Amanpour sat down with MacGregor at the Smithsonian's Sackler Gallery in Washington, D.C., the first leg of a five-city tour for the cylinder.

The Cyrus Cylinder was a charter created during the reign of Cyrus the Great, a Persian ruler whose kingdom covered much of modern-day Middle East.

In 539 B.C., Cyrus' forces conquered the great city of Babylon. Notably, Cyrus was not only tolerant of his new Babylonian subjects, but freed the city's Jewish captives and allowed them to return to their homeland, where they rebuilt the temple in Jerusalem.

"Most people know the story from the Hebrew Bible," MacGregor said. "This is the story from the other side, from the Persian end.

"What [Cyrus] represents is the first recognition that if you're going to run a society with different languages, different beliefs, you cannot impose by force one system," MacGregor said. "You need to find a way to get the consent of different peoples by recognizing their diversity."

Cyrus' legacy of statecraft was so important that he influenced history for millennia. Thomas Jefferson had two copies of the biography of Cyrus in his vast personal library. And there is a replica of the cylinder at the United Nations headquarters in New York.

The Cyrus Cylinder represents a time in history when Cyrus and the Iranians were seen as the good rulers - perhaps hard to believe with the current strained relations between Israel and Iran and the United States and Iran.

MacGregor called the current-day situation an "an odd historical phenomenon" and said understanding Iranian history is even more important.

Taken together, MacGregor said, the Cyrus Cylinder, Magna Carta and the U.S. Constitution are "a dream of what a society could be, of what a society should be."

The Cyrus Cylinder is on view at the Sackler Gallery until the end of April, and then makes its way to museums in Houston, New York, San Francisco and Los Angeles.