The large number of pottery artifacts found near Ogi in the South of the island demonstrate that Sado was populated as early as the Jōmon period.

In 1185, the designated representative Shugo for Sado, Osaragi, appointed Honma Yoshihisa as his shugodai (delegate) for the province.

When direct control from mainland Japan started around the 8th century, the island's remoteness meant that it soon became a place of banishment for difficult or inconvenient Japanese figures.

[1] The Buddhist monk Nichiren lived on Sado close to the present village Niibo in Kuninaka Plain from 1271 to 1274.

Sado experienced a sudden economic boom during the Edo period when gold was found in 1601 at Aikawa (相川).

A manpower shortage led to a second wave of "exiles" coming to Sado, although this time it was not imposed as a sentence for a committed crime.

By sending homeless people (the number of whom was growing in Japanese cities at the time) to Sado from the 18th century, the Shogunate hoped to kill two birds with one stone.

The Sado mine at its peak in the Edo era produced around 400 kilograms (1,100 troy pounds) of gold a year (as well as some silver).

A few months after World War II, on 18 January 1946, a Douglas Dakota (C-47) Sister Ann in British RAF service made an emergency landing on the island.

The highest point in Kosado is Ōjiyama (大地山) at 645 m. The plain in between is called Kuninaka (国中) and is the most populated area.

Lake Kamo (加茂湖), on the eastern side of Kuninaka, is filled with salt water, and is a growing place for oysters.

Similar trends have been common in other remote locations of Japan since World War II as younger generations have moved to more urban areas.

[8][9][10] Its rich history and relaxed rural atmosphere make Sado one of the major tourist destinations in Niigata Prefecture.

The island has several temples and historical ruins, and offers possibilities for various outdoor activities, as well as fresh local food.

As of June 2022, approximately 480 crested ibis have been observed making a radical comeback for their species, thanks to conservation efforts.

The group lives on the island, touring eight months a year, and in August they invite international artists to collaborate with them at their festival on Sado.

The Sado tourism industry suffered direct (though limited) as well as indirect damage from the 2004 Chūetsu earthquake, as access routes inside Niigata Prefecture were cut.